Jamal  Lemke

Jamal Lemke

1600668000

Dart DateTime 12 Hour Format AM and PM

So you want to see AM and PM in your time using the DateTime Object. It’s simple and I can explain it in 1 minute!

#dart

What is GEEK

Buddha Community

Dart DateTime 12 Hour Format AM and PM
Bulah  Pfeffer

Bulah Pfeffer

1648873833

A Collection of Flutter and Dart Tips and Tricks

Table of Contents

  • LazyStream in Flutter and Dart
  • Cancelable APIs in Flutter
  • Asset Data in Flutter
  • API Caching in Flutter
  • FutureGroup in Dart
  • Flatten Iterable<bool> in Dart
  • Caching Temp Files in Flutter
  • Custom Lists in Dart
  • Optional Chaining in Dart
  • MapList in Flutter
  • Future<bool> in Flutter
  • Async Bloc Init in Flutter
  • Firebase Auth Errors in Flutter
  • Debug Strings in Flutter
  • Keyboard Appearance in Flutter
  • Get String Data in Dart
  • Stream.startWith in Flutter
  • Optional Functions in Dart
  • AnnotatedRegion in Flutter
  • Unordered Map Equality in Dart
  • Iterable to ListView in Flutter
  • Password Mask in Flutter
  • Fast Object.toString() in Dart
  • Copying Bloc State in Flutter
  • Iterable Subscripts in Dart
  • useState in Flutter Hooks
  • Folding Iterables in Dart
  • Custom Iterables in Dart
  • Class Clusters in Dart
  • Iterable +/- in Dart
  • Periodic Streams in Dart
  • EmptyOnError in Dart
  • Stream<T> Initial Value in Flutter
  • Double.normalize in Dart
  • Hide Sensitive Information in Flutter
  • Iterable.compactMap in Dart
  • useEffect in Flutter Hooks
  • Merging Streams in Dart
  • Isolate Stream in Dart
  • Network Image Retry in Flutter
  • Reusable APIs in Flutter
  • ListTile Shadow in Flutter
  • Transparent AppBar in Flutter
  • Constructors on Abstract Classes in Dart
  • @useResult in Dart
  • @mustCallSuper in Dart
  • Object.hash in Dart
  • Expanded Equally in Flutter
  • Random Iterable Value in Dart
  • Hardcoded Strings in Flutter
  • Manually Scroll in List View in Flutter
  • AsyncSnapshot to Widget in Flutter
  • Breadcrumbs in Flutter
  • Unique Map Values in Dart
  • Smart Quotes/Dashes in Flutter
  • Haptic Feedback in Flutter
  • Localization Delegates in Flutter
  • Extending Functions in Dart
  • Paginated ListView in Flutter
  • Immutable Classes in Dart
  • Card Widget in Flutter
  • List Equality Ignoring Ordering in Dart
  • Shorten GitHub URLs in Dart
  • Time Picker in Flutter
  • Throttled Print in Flutter
  • Map Equality in Dart
  • Unique Maps in Dart
  • Raw Auto Complete in Flutter
  • Title on Object in Dart
  • Compute in Flutter
  • Filter on Map in Dart
  • Type Alias in Dart
  • ValueNotifier in Flutter
  • Object to Integer in Dart
  • Image Opacity in Flutter
  • Covariant in Dart
  • Custom Errors in Streams in Dart
  • Shake Animation in Flutter
  • Throw Enums in Dart
  • Future Error Test in Flutter
  • Generic URL Retrieval in Dart
  • Custom Error Widget in Flutter
  • Handle Multiple Future Errors in Dart
  • Future Error Handling in Dart
  • String to Toast in Flutter
  • Waiting in Dart
  • Loading Dialog in Flutter
  • Compact Map on Map<K,V> in Dart
  • Query Parameters in Dart
  • Multiple Gradients in Container in Flutter
  • Filter on Stream<List<T>> in Dart
  • Generic Route Arguments in Flutter
  • Generic Dialog in Flutter
  • GitHub API in Flutter
  • ChangeNotifier in Flutter
  • Refresh Indicator in Flutter
  • FlatMap in Dart
  • OrientationBuilder in Flutter
  • Linear Gradient in Flutter
  • Bloc Text Editing Controller in Flutter
  • Blurred TabBar in Flutter
  • Play YouTube in Flutter
  • ListView Background in Flutter
  • Integer to Binary in Dart
  • Split String by Length in Dart
  • Image Tint in Flutter
  • SlideTransition in Flutter
  • Expansion Panels and Lists in Flutter
  • Complete CRUD App in Flutter
  • SQLite Storage in Flutter
  • Circular Progress with Percentage in Flutter
  • Opening URLs in Flutter
  • Commodore 64 Screen in Flutter
  • Animated Lists in Flutter
  • CheckboxListTile in Flutter
  • - Operator on String in Dart
  • Dart Progress for Future<T>
  • Move Widget Shadows with Animation
  • Gallery with Blurred Backgrounds in Flutter
  • Custom Path Clippers in Flutter
  • Frost Effect on Images in Flutter
  • Custom Clippers in Flutter
  • Check if Website is Up or Down in Dart
  • Section Titles on ListView in Flutter
  • Circular Progress in Flutter
  • Displaying Scroll Wheels in Flutter
  • Post Messages to Slack with Dart
  • Unwrap List<T?>? in Dart
  • Avoiding UI Jitters When Switching Widgets in Flutter
  • Detect Redirects in Dart
  • Proportional Constraints in Flutter
  • Displaying Cupertino Action Sheets in Flutter
  • Rotating List<T> in Dart
  • Displaying SnackBars in Flutter
  • Custom Tab Bar Using ToggleButtons in Flutter
  • Hashable Mixins in Dart
  • Flutter Tips and Tricks in Terminal
  • Searching List<List<T>> in Dart
  • Cloning Objects in Dart
  • Color Filters in Flutter
  • Flattening Lists in Dart
  • Managing Duplicates in List<T> in Dart
  • FlatMap and CompactMap in Dart
  • Equality of List<T> in Dart
  • Constants in Dart
  • Displaying Scrollable Bottom Sheets in Flutter
  • YouTube Ad Remover in Dart
  • Fade Between Widgets in Flutter
  • Sort Descriptors in Dart
  • User Sortable Columns and Tables in Flutter
  • Content-Length of List<Uri> in Dart
  • Recursive Dot Notation on Maps in Dart
  • Allow User Selection of Text in Flutter
  • Placing Constraints on Widgets in Flutter
  • Animating Position Changes in Flutter
  • Transitioning Between Widgets in Flutter
  • Doubly Linked Lists in Dart
  • Reordering Items Inside List Views in Flutter
  • Custom Stream Transformers in Dart
  • Expanding Stream Elements in Dart
  • Consume Streams for a Duration in Dart
  • Shortening URLs in Dart
  • LimitedBox Widget as ListView Items in Flutter
  • Generically Convert Anything to Int in Dart
  • Validating URL Certificates in Dart
  • Displaying Popup Menus in Flutter
  • Implementing Drag and Drop in Flutter
  • Dismissing List Items in Flutter
  • Animating Widgets with Ease in Flutter
  • Displaying Tool Tips in Flutter
  • Displaying Assorted Widgets Inside TableView in Flutter
  • Page Indicator with Page View in Flutter
  • Animating and Moving a Floating Action Button in Flutter
  • Fading Network Image Widget in Flutter
  • Transparent Alert Dialogs in Flutter
  • Network Image Size in Dart
  • Animated Icons in Flutter
  • Custom Scroll Views in Flutter
  • Parallax App Bar in Flutter
  • JSON HTTP Requests in Dart
  • URL Timeouts in Dart
  • Detecting URL File Types in Dart
  • Paginated Lists in Dart
  • Requesting DELETE on APIs in Dart
  • Animated Containers in Flutter
  • Hiding Widgets in Flutter
  • Simple Opacity Animation in Flutter
  • Vignette Widget in Flutter
  • Drop Down Button Configuration and Usage in Flutter
  • Expandable List Items in Flutter
  • Infinite Scrolling in Flutter
  • Infinite Arrays in Dart
  • Custom Color Picker Component in Flutter
  • Displaying and Reacting to Switches in Flutter
  • Displaying Bottom Bars in Flutter
  • Displaying Buttons on AppBar in Flutter
  • Displaying Bottom Sheets in Flutter
  • Converting Enums to Radio Buttons in Flutter
  • Check Existence of Websites in Flutter
  • Images inside AlertDialog in Flutter
  • Returning Values from AlertDialog in Flutter
  • Simple Grid View in Flutter
  • Rendering Bullet Points in Flutter
  • Retrying Futures in Flutter
  • Containers as ClipOvals in Flutter
  • Rich Texts in Flutter
  • Wrapping Widgets in Flutter
  • Sweep Gradients in Flutter
  • Stream and StreamBuilder in Flutter
  • Blur Effect in Flutter
  • Convert Enums to Strings in Dart
  • Replacing Text in TextField in Flutter
  • Aspect Ratio in Flutter
  • Zoom and Pan in Flutter
  • Resizing Images in Flutter to Fit Screen Height
  • Validating URLs in Flutter
  • FrameBuilder for Network Images in Flutter
  • Adding Shadow to Icons in Flutter
  • Calculating Median of Lists in Dart
  • Generic Functions with Reduce in Dart
  • Passing Back Data From a Screen to the Previous One in Flutter
  • Flinging an Animation in Flutter
  • Fade Animations in Flutter
  • Throttling User Input in Flutter
  • Censoring TextFields in Flutter
  • Customizing TextButton in Flutter
  • Multiline TextFields in Flutter
  • Filtering TextField Input in Flutter
  • Focusing Manually on TextFields in Flutter
  • Data Streams Over HTTP/HTTPs in Dart
  • Catching Nonexistent Accessors or Methods in Dart
  • Using Expando in Dart
  • Implementing Custom Maps in Dart
  • Dynamically Calling Functions in Dart
  • Factory Constructors in Dart
  • Calculating the Sum of List Items in Dart
  • Removing Duplicate Strings in Lists in Dart (Case-Insensitive)
  • Implementing Range in Dart
  • Converting Lists to Maps in Dart
  • Implementing Hashable in Dart
  • Random Name Generator in Dart
  • Capturing Stack Traces in Dart Exceptions
  • Removing Duplicates from Lists in Dart
  • Optional Spread Operator in Dart
  • Calling Optional Functions in Dart
  • Odd-Even Sort in Dart
  • Implementing Zip and Tuples in Dart
  • Swapping Values in Lists with XOR in Dart
  • Waiting for Multiple Futures in Dart
  • Using Queues as Stacks in Dart
  • Custom Iterators in Dart
  • Iterables as Ranges + Transform in Dart
  • Errors vs Exceptions in Dart
  • Custom Annotations in Dart
  • Classes as Enums in Dart
  • Spread Operator in Collection Literals in Dart
  • StreamBuilder and StreamController in Dart
  • Almost Equal in Dart
  • Enum Associated Values in Dart
  • Implementing Comparable in Dart
  • Implementing Custom Integer Types in Dart
  • Custom Subscripts in Dart
  • Dart List Enumeration with Index
  • Applying Mixins to Other Mixins in Dart
  • Parameter Types in Dart
  • Custom Exceptions in Dart
  • rethrowing Exceptions in Dart
  • mixins and JSON Parsing in Dart
  • mixins vs abstract classes in Dart
  • Drawing Shapes in Flutter with LayoutBuilder, CustomPaint and CustomPainter
  • Generic Type Aliases in Dart
  • Callable Classes in Dart
  • Synchronous Generators in Dart
  • Implicit Interfaces in Dart
  • const Constructors in Dart
  • async-await Over Raw Futures in Dart
  • Initializer List and Default Values as Convenience Intializers in Dart
  • Extract Elements of Certain Type from Lists in Dart
  • Type Promotion in Dart
  • Extract Minimum and Maximum Values in List<num> in Dart
  • Functions as First Class Citizens in Dart

 

LazyStream in Flutter and Dart



import 'dart:developer' as devtools show log;
import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show NetworkAssetBundle, rootBundle;
import 'package:async/async.dart' show LazyStream;

extension LocalFileData on String {
  Future<Uint8List> localFileData() => rootBundle.load(this).then(
        (byteData) => byteData.buffer.asUint8List(),
      );
}

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() async {
  final stream = LazyStream(
    () async {
      final allData = await calculateAllData();
      return getImagesData(allData);
    },
  );

  await for (final data in stream) {
    'Got data, length = ${data.length}'.log();
  }
}

Stream<Uint8List> getImagesData(
  List<Future<Uint8List>> allData,
) async* {
  for (final data in allData) {
    yield await data;
  }
}

Future<List<Future<Uint8List>>> calculateAllData() async {
  final futures = Iterable.generate(
    3,
    (i) => 'images/image_list${i + 1}.txt'
        .localFileData()
        .then((data) => String.fromCharCodes(data)),
  );
  final result = Future.wait(futures);
  final lineSplitter = const LineSplitter();
  List<Future<Uint8List>> allData = [];
  for (final string in await result) {
    final urls = lineSplitter.convert(string);
    for (final url in urls) {
      allData.add(
        NetworkAssetBundle(Uri.parse(url))
            .load(url)
            .then((byteData) => byteData.buffer.asUint8List()),
      );
    }
  }
  return allData;
}

Cancelable APIs in Flutter

import 'dart:developer' as devtools show log;
import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show NetworkAssetBundle, rootBundle;
import 'package:async/async.dart' show CancelableOperation;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension LocalFileData on String {
  Future<Uint8List> localFileData() => rootBundle.load(this).then(
        (byteData) => byteData.buffer.asUint8List(),
      );
}

CancelableOperation<Uint8List> getImageOperation(String url) =>
    CancelableOperation.fromFuture(
      NetworkAssetBundle(Uri.parse(url))
          .load(url)
          .then((byteData) => byteData.buffer.asUint8List()),
      onCancel: () => 'images/template.png'.localFileData(),
    );

void testIt() async {
  final operation = getImageOperation('http://127.0.0.1:5500/images/1.png');
  final cancelledValue = await operation.cancel();
  final result = await operation.valueOrCancellation(cancelledValue);
  result?.log();
}

Asset Data in Flutter


import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show rootBundle;
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension LocalFileData on String {
  Future<Uint8List> localFileData() => rootBundle.load(this).then(
        (byteData) => byteData.buffer.asUint8List(),
      );
}

void testIt() async {
  (await 'images/template.png'.localFileData()).log();
}

API Caching in Flutter


import 'dart:typed_data' show Uint8List;
import 'package:flutter/services.dart' show NetworkAssetBundle;
import 'dart:developer' as devtools show log;
import 'package:async/async.dart' show AsyncMemoizer;

extension Log on Object {
  void log() => devtools.log(toString());
}

@immutable
class GetImageApi {
  final String url;
  final _fetch = AsyncMemoizer<Uint8List>();

  GetImageApi({required this.url});
  Future<Uint8List> fetch() => _fetch.runOnce(
        () => NetworkAssetBundle(Uri.parse(url))
            .load(url)
            .then((byteData) => byteData.buffer.asUint8List()),
      );
}

void testIt() async {
  final api = GetImageApi(url: 'http://127.0.0.1:5500/images/1.png');
  (await api.fetch()).log(); // fetched
  (await api.fetch()).log(); // cached
}

FutureGroup in Dart



mixin FutureConvertible<T> {
  Future<T> toFuture();
}

@immutable
class LoginApi with FutureConvertible<bool> {
  @override
  Future<bool> toFuture() => Future.delayed(
        const Duration(seconds: 1),
        () => true,
      );
}

@immutable
class SignUpApi with FutureConvertible<bool> {
  @override
  Future<bool> toFuture() => Future.delayed(
        const Duration(seconds: 1),
        () => true,
      );
}

extension Flatten on Iterable<bool> {
  bool flatten() => fold(
        true,
        (lhs, rhs) => lhs && rhs,
      );
}

extension Log on Object {
  void log() => devtools.log(toString());
}

Future<bool> startup({
  required bool shouldLogin,
  required bool shouldSignUp,
}) {
  final group = FutureGroup<bool>();
  if (shouldLogin) {
    group.add(LoginApi().toFuture());
  }
  if (shouldSignUp) {
    group.add(SignUpApi().toFuture());
  }
  group.close();
  return group.future.then((bools) => bools.flatten());
}

void testIt() async {
  final success = await startup(
    shouldLogin: true,
    shouldSignUp: false,
  );
  success.log();
}

Flatten Iterable<bool> in Dart


extension Flatten on Iterable<bool> {
  bool flatten() => fold(
        true,
        (lhs, rhs) => lhs && rhs,
      );
}

void testIt() {
  assert([true, false, true].flatten() == false);
  assert([true, true, true].flatten() == true);
  assert([false, false, false].flatten() == false);
  assert([true].flatten() == true);
  assert([false].flatten() == false);
}

Caching Temp Files in Flutter



@immutable
class NetworkImageAsset {
  final String localPath;
  final String url;
  NetworkImageAsset({required int index})
      : localPath = Directory.systemTemp.path + '/$index.png',
        url = 'http://127.0.0.1:5500/images/$index}.png';

  Future<bool> downloadAndSave() => NetworkAssetBundle(Uri.parse(url))
      .load(url)
      .then((byteData) => byteData.buffer.asUint8List())
      .then((data) => File(localPath).writeAsBytes(data).then((_) => true))
      .catchError((_) => false);
}

void testIt() async {
  await Future.forEach(
    Iterable.generate(
      3,
      (i) => NetworkImageAsset(index: i + 1),
    ),
    (NetworkImageAsset asset) => asset.downloadAndSave(),
  );
}

Custom Lists in Dart



import 'dart:developer' as devtools show log;
import 'dart:collection' show ListBase;

class LowercaseList extends ListBase<String> {
  final List<String> _list = [];

  @override
  int get length => _list.length;
  @override
  set length(int newLength) => _list.length = newLength;

  @override
  String operator [](int index) => _list[index].toUpperCase();

  @override
  void operator []=(int index, value) => _list[index] = value;

  @override
  void addAll(Iterable<String> iterable) => _list.addAll(iterable);

  @override
  void add(String element) => _list.add(element);
}

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() {
  final myList = LowercaseList();
  myList.addAll(['foo', 'bar', 'baz']);
  myList[0].log(); // FOO
  myList[1].log(); // BAR
  for (final item in myList) {
    item.log(); // FOO, BAR, BAZ
  }
}

Optional Chaining in Dart



@immutable
class Address {
  final String? firstLine;
  final String? secondLine;
  const Address(this.firstLine, this.secondLine);
}

@immutable
class Person {
  final Person? father;
  final Address? address;
  const Person(this.father, this.address);
}

extension GetFathersFirstAddressLine on Person {
  String? get firstAddressLineOfFather => father?.address?.firstLine;
}

MapList in Flutter



extension MapToList<T> on Iterable<T> {
  List<E> mapList<E>(E Function(T) toElement) => 
    map(toElement).toList();
}

Future<bool> in Flutter



Future<bool> uploadImage({
  required File file,
  required String userId,
}) =>
    FirebaseStorage.instance
        .ref(userId)
        .child(const Uuid().v4())
        .putFile(file)
        .then((_) => true)
        .catchError((_) => false);

Async Bloc Init in Flutter



class App extends StatelessWidget {
  const App({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return BlocProvider<AppBloc>(
      create: (context) => AppBloc()..add(const AppEventInitialize()),
      child: MaterialApp(
        title: 'Photo Library',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        debugShowCheckedModeBanner: false,
        home: BlocConsumer<AppBloc, AppState>(
          listener: (context, state) {
            // handle loading
            if (state.isLoading) {
              LoadingScreen().show(
                context: context,
                text: 'Loading...',
              );
            } else {
              LoadingScreen().hide();
            }
            
            ... rest of your code goes here

Firebase Auth Errors in Flutter



const authErrorMapping = {
  'user-not-found': AuthErrorUserNotFound(),
  'project-not-found': AuthErrorProjectNotFound(),
};

@immutable
abstract class AuthError {
  factory AuthError.from(FirebaseAuthException exception) =>
      authErrorMapping[exception.code.toLowerCase().trim()] ??
      const AuthErrorUnknown();
}

@immutable
class AuthErrorUnknown implements AuthError {
  const AuthErrorUnknown();
}

@immutable
class AuthErrorUserNotFound implements AuthError {
  const AuthErrorUserNotFound();
}

@immutable
class AuthErrorProjectNotFound implements AuthError {
  const AuthErrorProjectNotFound();
}

Debug Strings in Flutter


extension IfDebugging on String {
  String? get ifDebugging => kDebugMode ? this : null;
}

class LoginView extends HookWidget {
  const LoginView({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final emailController = useTextEditingController(
      text: 'foo@bar.com'.ifDebugging,
    );
    final passwordController = useTextEditingController(
      text: 'foobarbaz'.ifDebugging,
    );
    
    // rest of your code would be here ...

Keyboard Appearance in Flutter


class LoginView extends HookWidget {
  const LoginView({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Log in'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: const [
            TextField(
              keyboardType: TextInputType.emailAddress,
              keyboardAppearance: Brightness.dark,
            ),
            TextField(
              obscureText: true,
              obscuringCharacter: 'β—‰',
            ),
          ],
        ),
      ),
    );
  }
}

Get String Data in Dart


extension ToList on String {
  Uint8List toUint8List() => Uint8List.fromList(codeUnits);
}

final text1Data = 'Foo'.toUint8List();
final text2Data = 'Bar'.toUint8List();

Stream.startWith in Flutter


import 'package:async/async.dart' show StreamGroup;
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension StartWith<T> on Stream<T> {
  Stream<T> startWith(T value) => StreamGroup.merge([
        this,
        Stream<T>.value(value),
      ]);
}

void testIt() {
  Stream.periodic(const Duration(seconds: 1), (i) => i + 1)
      .startWith(0)
      .take(4)
      .forEach((element) {
    element.log();
  }); // 0, 1, 2, 3
}

Optional Functions in Dart



typedef AppBlocRandomUrlPicker = String Function(Iterable<String> allUrls);

extension RandomElement<T> on Iterable<T> {
  T getRandomElement() => elementAt(
        math.Random().nextInt(length),
      );
}

class AppBloc extends Bloc<AppEvent, AppState> {
  String _pickRandomUrl(Iterable<String> allUrls) => allUrls.getRandomElement();

  AppBloc({
    required Iterable<String> urls,
    AppBlocRandomUrlPicker? urlPicker,
  }) : super(const AppState.empty()) {
    on<LoadNextUrlEvent>(
      (event, emit) {
        emit(
          const AppState(
            isLoading: true,
            data: null,
          ),
        );
        // pick a random URL to load
        final url = (urlPicker ?? _pickRandomUrl)(urls);
        HttpClient().getUrl(Uri.parse(url)); // continue here...
      },
    );
  }
}

AnnotatedRegion in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: AnnotatedRegion<SystemUiOverlayStyle>(
        value: SystemUiOverlayStyle.dark,
        child: Column(
          mainAxisSize: MainAxisSize.max,
          children: [
            Expanded(child: Container(color: Colors.blue)),
            Expanded(child: Container(color: Colors.yellow)),
          ],
        ),
      ),
    );
  }
}

Unordered Map Equality in Dart



import 'package:collection/collection.dart';
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension UnorderedEquality<K, V> on Map<K, V> {
  bool isEqualTo(Map<K, V> other) =>
      const DeepCollectionEquality.unordered().equals(this, other);
}

void testIt() {
  final dict1 = {
    'name': 'foo',
    'age': 20,
    'values': ['foo', 'bar'],
  };
  final dict2 = {
    'age': 20,
    'name': 'foo',
    'values': ['bar', 'foo'],
  };
  dict1.isEqualTo(dict2).log(); // true
}

Iterable to ListView in Flutter



extension ToListView<T> on Iterable<T> {
  Widget toListView() => IterableListView(
        iterable: this,
      );
}

class IterableListView<T> extends StatelessWidget {
  final Iterable<T> iterable;
  const IterableListView({
    Key? key,
    required this.iterable,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: iterable.length,
      itemBuilder: (context, index) {
        return ListTile(
          title: Text(
            iterable.elementAt(index).toString(),
          ),
        );
      },
    );
  }
}

@immutable
class Person {
  final String name;
  final int age;
  const Person({required this.name, required this.age});
  @override
  String toString() => '$name, $age years old';
}

const persons = [
  Person(name: 'Foo', age: 20),
  Person(name: 'Bar', age: 30),
  Person(name: 'Baz', age: 40),
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: persons.toListView(),
    );
  }
}

Password Mask in Flutter



class PasswordTextField extends StatelessWidget {
  const PasswordTextField({
    Key? key,
    required this.passwordController,
  }) : super(key: key);

  final TextEditingController passwordController;

  @override
  Widget build(BuildContext context) {
    return TextField(
      controller: passwordController,
      obscureText: true,
      obscuringCharacter: 'β—‰',
      decoration: const InputDecoration(
        hintText: 'Enter your password here...',
      ),
    );
  }
}

Fast Object.toString() in Dart



@immutable
class AppState {
  final bool isLoading;
  final Object? loginError;
  final String? loginHandle;
  final Iterable<String>? fetchedNotes;

  @override
  String toString() => {
        'isLoading': isLoading,
        'loginError': loginError,
        'loginHandle': loginHandle,
        'fetchedNotes': fetchedNotes
      }.toString();

  const AppState({
    required this.isLoading,
    required this.loginError,
    required this.loginHandle,
    required this.fetchedNotes,
  });
}

Copying Bloc State in Flutter



@immutable
class AppState {
  final bool isLoading;
  final LoginHandle? loginHandle;
  final Iterable<Note>? fetchedNotes;

  const AppState.empty()
      : isLoading = false,
        loginHandle = null,
        fetchedNotes = null;

  const AppState({
    required this.isLoading,
    required this.loginHandle,
    required this.fetchedNotes,
  });

  AppState copiedWith({
    bool? isLoading,
    LoginHandle? loginHandle,
    Iterable<Note>? fetchedNotes,
  }) =>
      AppState(
        isLoading: isLoading ?? this.isLoading,
        loginHandle: loginHandle ?? this.loginHandle,
        fetchedNotes: fetchedNotes ?? this.fetchedNotes,
      );
}

Iterable Subscripts in Dart

// Free Flutter Course πŸ’™ https://linktr.ee/vandadnp
// Want to support my work 🀝? https://buymeacoffee.com/vandad

import 'dart:developer' as devtools show log;

extension Log on Object? {
  void log() => devtools.log(toString());
}

extension Subscript<T> on Iterable<T> {
  T? operator [](int index) => length > index ? elementAt(index) : null;
}

void testIt() {
  Iterable.generate(10, (i) => i + 1)[0].log(); // 1
  Iterable.generate(1, (i) => i)[2].log(); // null
  Iterable.generate(10, (i) => i + 1)[9].log(); // 10
  Iterable.generate(0, (i) => i)[0].log(); // null
}

useState in Flutter Hooks



import 'package:flutter_hooks/flutter_hooks.dart';
import 'dart:math' show min;

@immutable
class VirtualTab {
  final Icon icon;
  final String text;

  const VirtualTab({
    required this.icon,
    required this.text,
  });
}

const tabs = [
  VirtualTab(
    icon: Icon(Icons.picture_as_pdf),
    text: 'All PDF files',
  ),
  VirtualTab(
    icon: Icon(Icons.ac_unit_outlined),
    text: 'Data page',
  ),
  VirtualTab(
    icon: Icon(Icons.person),
    text: 'Profile page',
  ),
];

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final tabCount = useState(1);
    return DefaultTabController(
      length: tabCount.value,
      initialIndex: tabCount.value - 1,
      child: Scaffold(
        appBar: AppBar(
          bottom: TabBar(
            tabs: tabs
                .take(tabCount.value)
                .map((tab) => Tab(icon: tab.icon))
                .toList(),
          ),
        ),
        body: CustomTabBarView(tabCount: tabCount),
      ),
    );
  }
}

class CustomTabBarView extends StatelessWidget {
  const CustomTabBarView({
    Key? key,
    required this.tabCount,
  }) : super(key: key);

  final ValueNotifier<int> tabCount;

  @override
  Widget build(BuildContext context) {
    return TabBarView(
      children: tabs
          .take(tabCount.value)
          .map(
            (tab) => Padding(
              padding: const EdgeInsets.all(8.0),
              child: Column(
                children: [
                  Text(tab.text),
                  TextButton(
                    onPressed: () {
                      final newLength = min(
                        tabs.length,
                        tabCount.value + 1,
                      );
                      tabCount.value = newLength;
                    },
                    child: const Text('Create next tab'),
                  )
                ],
              ),
            ),
          )
          .toList(),
    );
  }
}

 

Folding Iterables in Dart



import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() {
  final values = ['foo', 'bar', 'baz', '1.0'];

  values.fold<int>(0, (pe, e) => pe + e.length); // 12

  values.fold<String>('', (pe, e) => '$pe$e'); // foobarbaz1.0

  values.fold<Map<String, int>>(
    {},
    (pe, e) => pe..addAll(<String, int>{e: e.length}),
  ).log(); // {foo: 3, bar: 3, baz: 3, 1.0: 3}

  values.fold<double>(
    0.0,
    (pe, e) => pe + (double.tryParse(e) ?? 0.0),
  ); // 1.0
}

Custom Iterables in Dart



class Address with IterableMixin {
  final String line1;
  final String line2;
  final String postCode;

  Address({
    required this.line1,
    required this.line2,
    required this.postCode,
  });

  @override
  Iterator<String> get iterator => [line1, line2, postCode].iterator;
}

void testIt() {
  final address = Address(
    line1: 'Foo bar avenue, #10',
    line2: 'Baz street',
    postCode: '123456',
  );
  for (final line in address) {
    devtools.log(line);
  }
}

Class Clusters in Dart



enum AnimalType { dog, cat }

@immutable
abstract class Animal {
  const Animal();
  factory Animal.fromType(AnimalType type) {
    switch (type) {
      case AnimalType.dog:
        return const Dog();
      case AnimalType.cat:
        return const Cat();
    }
  }
  void makeNoise();
}

@immutable
class Dog extends Animal {
  const Dog();
  @override
  void makeNoise() => 'Woof'.log();
}

@immutable
class Cat extends Animal {
  const Cat();
  @override
  void makeNoise() => 'Meow'.log();
}

void testIt() {
  final cat = Animal.fromType(AnimalType.cat);
  cat.makeNoise();
  final dog = Animal.fromType(AnimalType.dog);
  dog.makeNoise();
}

Iterable +/- in Dart



extension AddRemoveItems<T> on Iterable<T> {
  Iterable<T> operator +(T other) => followedBy([other]);
  Iterable<T> operator -(T other) => where((element) => element != other);
}

void testIt() {
  final values = ['foo', 'bar']
    .map((e) => e.toUpperCase()) + 'BAZ';
  values.log(); // (FOO, BAR, BAZ)
  (values - 'BAZ').log(); // (FOO, BAR)
}

Periodic Streams in Dart



import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:convert';
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

@immutable
class Person {
  final String name;
  final int age;

  const Person({
    required this.name,
    required this.age,
  });

  Person.fromJson(Map<String, dynamic> json)
      : name = json["name"] as String,
        age = json["age"] as int;

  @override
  String toString() => 'Person ($name, $age years old)';
}

mixin ListOfThingsAPI<T> {
  Future<Iterable<T>> get(String url) => HttpClient()
      .getUrl(Uri.parse(url))
      .then((req) => req.close())
      .then((resp) => resp.transform(utf8.decoder).join())
      .then((str) => json.decode(str) as List<dynamic>)
      .then((list) => list.cast());
}

class GetPeople with ListOfThingsAPI<Map<String, dynamic>> {
  Future<Iterable<Person>> getPeople(url) => get(url).then(
        (jsons) => jsons.map(
          (json) => Person.fromJson(json),
        ),
      );
}

Stream<dynamic> every(Duration duration) => Stream.periodic(duration);

extension IntToDuration on int {
  Duration get seconds => Duration(seconds: this);
}

void testIt() async {
  await for (final people in every(3.seconds).asyncExpand(
    (_) => GetPeople()
        .getPeople('http://127.0.0.1:5500/apis/people1.json')
        .asStream(),
  )) {
    people.log();
  }
}

/* people1.json
[
    {
        "name": "Foo 1",
        "age": 20
    },
    {
        "name": "Bar 1",
        "age": 30
    }
]
*/

EmptyOnError in Dart



import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:convert';
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

@immutable
class Person {
  final String name;
  final int age;

  const Person({
    required this.name,
    required this.age,
  });

  Person.fromJson(Map<String, dynamic> json)
      : name = json["name"] as String,
        age = json["age"] as int;

  @override
  String toString() => 'Person ($name, $age years old)';
}

const people1Url = 'http://127.0.0.1:5500/apis/people11.json';
const people2Url = 'http://127.0.0.1:5500/apis/people2.json';

extension EmptyOnError<E> on Future<List<Iterable<E>>> {
  Future<List<Iterable<E>>> emptyOnError() => catchError(
        (_, __) => List<Iterable<E>>.empty(),
      );
}

Future<Iterable<Person>> parseJson(String url) => HttpClient()
    .getUrl(Uri.parse(url))
    .then((req) => req.close())
    .then((resp) => resp.transform(utf8.decoder).join())
    .then((str) => json.decode(str) as List<dynamic>)
    .then((json) => json.map((e) => Person.fromJson(e)));

void testIt() async {
  final persons = await Future.wait([
    parseJson(people1Url),
    parseJson(people2Url),
  ]).emptyOnError();
  persons.log();
}

Stream<T> Initial Value in Flutter



import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

const url = 'https://bit.ly/3x7J5Qt';

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    late final StreamController<double> controller;
    controller = useStreamController<double>(onListen: () {
      controller.sink.add(0.0);
    });

    return Scaffold(
      appBar: AppBar(
        title: const Text('Home page'),
      ),
      body: StreamBuilder<double>(
          stream: controller.stream,
          builder: (context, snapshot) {
            if (!snapshot.hasData) {
              return const CircularProgressIndicator();
            } else {
              final rotation = snapshot.data ?? 0.0;
              return GestureDetector(
                onTap: () {
                  controller.sink.add(rotation + 10.0);
                },
                child: RotationTransition(
                  turns: AlwaysStoppedAnimation(rotation / 360.0),
                  child: Center(
                    child: Image.network(url),
                  ),
                ),
              );
            }
          }),
    );
  }
}

Double.normalize in Dart



import 'dart:developer' as devtools show log;

extension Normalize on double {
  double normalized(
    double selfRangeMin,
    double selfRangeMax, [
    double normalizedRangeMin = 0.0,
    double normalizedRangeMax = 1.0,
  ]) =>
      (normalizedRangeMax - normalizedRangeMin) *
          ((this - selfRangeMin) / (selfRangeMax - selfRangeMin)) +
      normalizedRangeMin;
}

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() async {
  2.0.normalized(0, 2.0).log(); // 1.0
  4.0.normalized(0, 8.0).log(); // 0.5
  5.0.normalized(4.0, 6.0, 10.0, 20.0).log(); // 15
}

Hide Sensitive Information in Flutter

 



import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final state = useAppLifecycleState();
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Opacity(
          opacity: state == AppLifecycleState.resumed ? 1.0 : 0.0,
          child: Container(
            decoration: BoxDecoration(
              boxShadow: [
                BoxShadow(
                  blurRadius: 10,
                  color: Colors.black.withAlpha(100),
                  spreadRadius: 10,
                ),
              ],
            ),
            child: Image.asset('assets/card.png'),
          ),
        ),
      ),
    );
  }
}

Iterable.compactMap in Dart



import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension CompactMap<T> on Iterable<T?> {
  Iterable<T> compactMap<E>([
    E? Function(T?)? transform,
  ]) =>
      map(transform ?? (e) => e).where((e) => e != null).cast();
}

const list = ['Hello', null, 'World'];

void testIt() {
  list.log(); // [Hello, null, World]
  list.compactMap().log(); // [Hello, World]
  list.compactMap((e) => e?.toUpperCase()).log(); // [HELLO, WORLD]
}

useEffect in Flutter Hooks



import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final controller = useTextEditingController();
    final text = useState('');
    useEffect(
      () {
        void listener() {
          text.value = controller.text;
        }

        controller.addListener(listener);
        return () => controller.removeListener(listener);
      },
      [controller],
    );
    return Scaffold(
      body: Column(
        children: [
          TextField(
            controller: controller,
          ),
          Text('You typed ${text.value}')
        ],
      ),
    );
  }
}

Merging Streams in Dart



import 'package:async/async.dart' show StreamGroup;
import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

void testIt() async {
  final streams = Iterable.generate(
    3,
    (i) => Stream.periodic(
      const Duration(seconds: 1),
      (_) => 'Stream $i: ${DateTime.now().toIso8601String()}',
    ).take(i + 1),
  );
  await for (final now in StreamGroup.merge(streams)) {
    now.log();
  }
}

Isolate Stream in Dart



Stream<String> getMessages() {
  final rp = ReceivePort();
  return Isolate.spawn(_getMessages, rp.sendPort)
      .asStream()
      .asyncExpand((_) => rp)
      .takeWhile((element) => element is String)
      .cast();
}

void _getMessages(SendPort sp) async {
  await for (final now in Stream.periodic(
    const Duration(seconds: 1),
    (_) => DateTime.now().toIso8601String(),
  ).take(10)) {
    sp.send(now);
  }
  Isolate.exit(sp);
}

void testIt() async {
  await for (final msg in getMessages()) {
    msg.log();
  }
}

Network Image Retry in Flutter



@immutable
class RetryStrategy {
  final bool shouldRetry;
  final Duration waitBeforeRetry;
  const RetryStrategy({
    required this.shouldRetry,
    required this.waitBeforeRetry,
  });
}

typedef Retrier = RetryStrategy Function(String url, Object error);

class NetworkImageWithRetry extends StatelessWidget {
  final Widget loadingWidget;
  final Widget errorWidget;
  final String url;
  final Retrier retrier;

  final _controller = StreamController<Uint8List>.broadcast();

  NetworkImageWithRetry({
    Key? key,
    required this.url,
    required this.retrier,
    required this.loadingWidget,
    required this.errorWidget,
  }) : super(key: key);

  void getData() async {
    while (true == true) {
      try {
        final networkAsset = NetworkAssetBundle(Uri.parse(url));
        final loaded = await networkAsset.load(url);
        final bytes = loaded.buffer.asUint8List();
        _controller.sink.add(bytes);
        break;
      } catch (e) {
        final strategy = retrier(url, e);
        if (strategy.shouldRetry) {
          await Future.delayed(strategy.waitBeforeRetry);
        } else {
          _controller.sink.addError(e);
          break;
        }
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    getData();
    return StreamBuilder(
      stream: _controller.stream,
      builder: (context, AsyncSnapshot<Uint8List> snapshot) {
        if (snapshot.hasError) {
          return errorWidget;
        } else {
          final data = snapshot.data;
          if (snapshot.hasData && data != null) {
            return Image.memory(data);
          } else {
            return loadingWidget;
          }
        }
      },
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Image Retry'),
      ),
      body: NetworkImageWithRetry(
        url: 'https://bit.ly/3qYOtDm',
        errorWidget: const Text('Got an error!'),
        loadingWidget: const Text('Loading...'),
        retrier: (url, error) {
          return RetryStrategy(
            shouldRetry: error is! FlutterError,
            waitBeforeRetry: const Duration(seconds: 1),
          );
        },
      ),
    );
  }
}

Reusable APIs in Flutter

import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:developer' as devtools show log;
import 'dart:convert' show utf8;
import 'package:meta/meta.dart' show useResult;

extension Log on Object {
  void log() => devtools.log(toString());
}

extension GetOnUri on Object {
  Future<HttpClientResponse> getUrl(
    String url,
  ) =>
      HttpClient()
          .getUrl(
            Uri.parse(
              url,
            ),
          )
          .then((req) => req.close());
}

mixin CanMakeGetCall {
  String get url;
  @useResult
  Future<String> getString() => getUrl(url).then(
        (response) => response
            .transform(
              utf8.decoder,
            )
            .join(),
      );
}

@immutable
class GetPeople with CanMakeGetCall {
  const GetPeople();
  @override
  String get url => 'http://127.0.0.1:5500/apis/people.json';
}

void testIt() async {
  final people = await const GetPeople().getString();
  devtools.log(people);
}

ListTile Shadow in Flutter



enum Currency { dollars }

extension Title on Currency {
  String get title {
    switch (this) {
      case Currency.dollars:
        return '\$';
    }
  }
}

@immutable
class Item {
  final IconData icon;
  final String name;
  final double price;
  final Currency currency;

  const Item({
    required this.icon,
    required this.name,
    required this.price,
    required this.currency,
  });

  String get description => '$price${currency.title}';
}

const items = [
  Item(
    icon: Icons.camera_alt,
    name: 'Camera',
    price: 300,
    currency: Currency.dollars,
  ),
  Item(
    icon: Icons.house,
    name: 'House',
    price: 1000000,
    currency: Currency.dollars,
  ),
  Item(
    icon: Icons.watch,
    name: 'Smart Watch',
    price: 200,
    currency: Currency.dollars,
  ),
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: ListView.builder(
        itemCount: items.length,
        itemBuilder: (_, index) {
          return ItemTile(
            item: items[index],
          );
        },
      ),
    );
  }
}

class ItemTile extends StatelessWidget {
  final Item item;
  const ItemTile({Key? key, required this.item}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Stack(
        children: [
          const TileBackground(),
          CustomTile(item: item),
        ],
      ),
    );
  }
}

class CustomTile extends StatelessWidget {
  final Item item;
  const CustomTile({
    Key? key,
    required this.item,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(bottom: 7.0),
      child: Container(
        decoration: customDecoration(),
        child: ListTile(
          leading: Icon(
            item.icon,
            color: Colors.white,
          ),
          title: Text(item.name),
          subtitle: Text(item.description),
        ),
      ),
    );
  }
}

BoxDecoration customDecoration() {
  return BoxDecoration(
    color: const Color.fromARGB(255, 0x7d, 0xcf, 0xff),
    borderRadius: BorderRadius.circular(10.0),
    border: Border.all(
      color: Colors.black,
      width: 2.0,
    ),
  );
}

class TileBackground extends StatelessWidget {
  const TileBackground({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Positioned.fill(
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 6.0),
        child: Container(
          decoration: BoxDecoration(
            color: const Color.fromARGB(255, 202, 255, 127),
            borderRadius: BorderRadius.circular(10.0),
            border: Border.all(
              color: Colors.black,
              width: 2.0,
            ),
          ),
        ),
      ),
    );
  }
}

Transparent AppBar in Flutter



const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      extendBodyBehindAppBar: true,
      appBar: AppBar(
        elevation: 0.0,
        backgroundColor: Colors.blueAccent.withAlpha(200),
        title: const Text('Transparent App Bar in Flutter'),
      ),
      body: const ImagesScrollView(),
    );
  }
}

class ImagesScrollView extends StatelessWidget {
  const ImagesScrollView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      padding: const EdgeInsets.only(top: 80.0),
      child: Padding(
        padding: const EdgeInsets.only(
          top: 40.0,
          left: 10.0,
          right: 10.0,
        ),
        child: Column(
          children: images
              .map((url) => ElevatedNetworkImage(url: url))
              .expand(
                (img) => [
                  img,
                  const SizedBox(height: 30.0),
                ],
              )
              .toList(),
        ),
      ),
    );
  }
}

class ElevatedNetworkImage extends StatelessWidget {
  final String url;
  const ElevatedNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return PhysicalShape(
      color: Colors.white,
      clipper: Clipper(),
      elevation: 20.0,
      clipBehavior: Clip.none,
      shadowColor: Colors.white.withAlpha(200),
      child: CutEdges(
        child: Image.network(url),
      ),
    );
  }
}

class Clipper extends CustomClipper<Path> {
  static const variance = 0.2;
  static const reverse = 1.0 - variance;

  @override
  Path getClip(Size size) {
    final path = Path();

    path.moveTo(0.0, size.height * Clipper.variance);
    path.lineTo(size.width * Clipper.variance, 0.0);
    path.lineTo(size.width, 0.0);
    path.lineTo(size.width, size.height * Clipper.reverse);
    path.lineTo(size.width * Clipper.reverse, size.height);
    path.lineTo(0.0, size.height);
    path.lineTo(0.0, size.height * Clipper.variance);
    path.close();
    return path;
  }

  @override
  bool shouldReclip(covariant CustomClipper<Path> oldClipper) => false;
}

class CutEdges extends StatelessWidget {
  final Widget child;

  const CutEdges({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ClipPath(
      clipper: Clipper(),
      child: child,
    );
  }
}

Constructors on Abstract Classes in Dart



import 'dart:developer' as devtools show log;

extension Log on Object {
  void log() => devtools.log(toString());
}

enum Type { dog, cat }

abstract class CanRun {
  final Type type;
  const CanRun({required this.type});
}

class Cat extends CanRun {
  const Cat() : super(type: Type.cat);
}

class Dog extends CanRun {
  const Dog() : super(type: Type.dog);
}

@useResult in Dart



import 'package:meta/meta.dart' show useResult;

class Person {
  final String firstName;
  final String lastName;

  const Person({
    required this.firstName,
    required this.lastName,
  });

  @useResult
  String fullName() => '$firstName $lastName';
}

void printFullName() {
  const Person(
    firstName: 'Foo',
    lastName: 'Bar',
  ).fullName();
}

@mustCallSuper in Dart



class Animal {
  @mustCallSuper
  void run() {}
}

class Dog extends Animal {
  @override
  void run() {}
}

Object.hash in Dart



class BreadCrumb {
  final bool isActive;
  final String name;
  BreadCrumb({
    required this.isActive,
    required this.name,
  });
  BreadCrumb activated() => BreadCrumb(
        isActive: true,
        name: name,
      );
  @override
  bool operator ==(covariant BreadCrumb other) =>
      isActive == other.isActive && name == other.name;

  @override
  int get hashCode => Object.hash(isActive, name);
}

Expanded Equally in Flutter



import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      debugShowCheckedModeBanner: false,
      home: const HomePage(),
    ),
  );
}

extension ExpandEqually on Iterable<Widget> {
  Iterable<Widget> expandedEqually() => map(
        (w) => Expanded(
          flex: 1,
          child: w,
        ),
      );
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home Page'),
      ),
      body: Column(
        children: [
          Row(
            mainAxisSize: MainAxisSize.max,
            children: [
              Container(
                height: 200,
                color: Colors.yellow,
              ),
              Container(
                height: 200,
                color: Colors.blue,
              ),
            ].expandedEqually().toList(),
          )
        ],
      ),
    );
  }
}

Random Iterable Value in Dart



import 'dart:math' as math show Random;

extension RandomElement<T> on Iterable<T> {
  T getRandomElement() => elementAt(
        math.Random().nextInt(length),
      );
}

final colors = [Colors.blue, Colors.red, Colors.brown];

class HomePage extends StatelessWidget {
  final color = ValueNotifier<MaterialColor>(
    colors.getRandomElement(),
  );
  HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('List.Random in Flutter'),
      ),
      body: ColorPickerButton(color: color),
    );
  }
}

class ColorPickerButton extends StatelessWidget {
  final ValueNotifier<MaterialColor> color;

  const ColorPickerButton({
    Key? key,
    required this.color,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder<Color>(
      valueListenable: color,
      builder: (context, value, child) {
        return Padding(
          padding: const EdgeInsets.all(8.0),
          child: CenteredTight(
            child: TextButton(
              style: TextButton.styleFrom(backgroundColor: value),
              onPressed: () {
                color.value = colors.getRandomElement();
              },
              child: const Text(
                'Change color',
                style: TextStyle(
                  fontSize: 30,
                  color: Colors.white,
                ),
              ),
            ),
          ),
        );
      },
    );
  }
}

Hardcoded Strings in Flutter



extension Hardcoded on String {
  String get hardcoded => '$this 🧨';
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'My hardcoded string'.hardcoded,
        ),
      ),
      body: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text('String in body'.hardcoded),
        ],
      ),
    );
  }
}

Manually Scroll in List View in Flutter

// Free Flutter Course πŸ’™ https://linktr.ee/vandadnp

import 'package:scrollable_positioned_list/scrollable_positioned_list.dart';

class HomePage extends StatelessWidget {
  final _controller = ItemScrollController();
  HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Testing'),
      ),
      body: ScrollablePositionedList.builder(
        itemScrollController: _controller,
        itemCount: allImages.length + 1,
        itemBuilder: (context, index) {
          if (index == 0) {
            return IndexSelector(
              count: allImages.length,
              onSelected: (index) {
                _controller.scrollTo(
                  index: index + 1,
                  duration: const Duration(milliseconds: 370),
                );
              },
            );
          } else {
            return ImageWithTitle(index: index);
          }
        },
      ),
    );
  }
}

class ImageWithTitle extends StatelessWidget {
  final int index;
  const ImageWithTitle({
    Key? key,
    required this.index,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text(
          'Image $index',
          style: const TextStyle(fontSize: 30.0),
        ),
        Image.network(allImages.elementAt(index - 1)),
      ],
    );
  }
}

typedef OnIndexSelected = void Function(int index);

class IndexSelector extends StatelessWidget {
  final int count;
  final OnIndexSelected onSelected;
  final String prefix;
  const IndexSelector({
    Key? key,
    required this.count,
    required this.onSelected,
    this.prefix = 'Image',
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      scrollDirection: Axis.horizontal,
      child: Row(
        children: Iterable.generate(
          count,
          (index) => TextButton(
            onPressed: () {
              onSelected(index);
            },
            child: Text('$prefix ${index + 1}'),
          ),
        ).toList(),
      ),
    );
  }
}

const imageUrls = [
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

AsyncSnapshot to Widget in Flutter



import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const HomePage(),
    ),
  );
}

final future = Future<String>.delayed(
  const Duration(seconds: 3),
  () => 'Hello world',
);

typedef ResolveToWidget<T> = Widget Function(
  ConnectionState connectionState,
  AsyncSnapshot<T> snapshot,
);

extension Materialize on AsyncSnapshot {
  Widget materialize(ResolveToWidget f) => f(
        connectionState,
        this,
      );
}

class HomePage extends HookWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Hooks'),
      ),
      body: useFuture(future).materialize((connectionState, snapshot) {
        switch (connectionState) {
          case ConnectionState.done:
            return Text(snapshot.data ?? '');
          default:
            return const CircularProgressIndicator();
        }
      }),
    );
  }
}

Breadcrumbs in Flutter



@immutable
class BreadCrumbPath {
  final String title;
  final bool isActive;
  const BreadCrumbPath({
    required this.title,
    required this.isActive,
  });
  BreadCrumbPath activated() {
    return BreadCrumbPath(
      title: title,
      isActive: true,
    );
  }

  @override
  String toString() => title;
}

class BreatCrumbPathView extends StatelessWidget {
  final BreadCrumbPath path;

  const BreatCrumbPathView({
    Key? key,
    required this.path,
  }) : super(key: key);
  @override
  Widget build(BuildContext context) {
    final title = path.isActive ? '${path.title} β†’' : path.title;
    return Padding(
      padding: const EdgeInsets.all(2.0),
      child: Text(
        title,
        style: TextStyle(
          height: 1.0,
          fontSize: 20.0,
          color: path.isActive ? Colors.blueAccent : Colors.black,
        ),
      ),
    );
  }
}

typedef OnBreadCrumbPathTapped = void Function(BreadCrumbPath path);

class BreadCrumbView extends StatelessWidget {
  final OnBreadCrumbPathTapped onTapped;
  final Stream<List<BreadCrumbPath>> paths;
  const BreadCrumbView({
    Key? key,
    required this.paths,
    required this.onTapped,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return StreamBuilder<List<BreadCrumbPath>>(
      stream: paths,
      builder: (context, snapshot) {
        final List<Widget> views;
        switch (snapshot.connectionState) {
          case ConnectionState.waiting:
          case ConnectionState.active:
            final paths = snapshot.data ?? [];
            final views = paths
                .map(
                  (path) => GestureDetector(
                    onTap: () => onTapped(path),
                    child: BreatCrumbPathView(path: path),
                  ),
                )
                .toList();
            return Wrap(
              spacing: 4.0,
              children: views,
              alignment: WrapAlignment.start,
              crossAxisAlignment: WrapCrossAlignment.center,
            );
          default:
            return Wrap();
        }
      },
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  List<BreadCrumbPath> _paths = [];
  late final TextEditingController _textController;
  late final StreamController<List<BreadCrumbPath>> _pathsController;

  @override
  void initState() {
    _pathsController = StreamController<List<BreadCrumbPath>>.broadcast(
      onListen: () {
        _pathsController.add(_paths);
      },
    );
    _textController = TextEditingController();
    super.initState();
  }

  @override
  void dispose() {
    _textController.dispose();
    _pathsController.close();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Breadcrumb in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            BreadCrumbView(
              paths: _pathsController.stream,
              onTapped: (path) async {
                await showBreadCrumbPathTappedDialog(
                  context,
                  path,
                );
              },
            ),
            TextField(
              controller: _textController,
              textAlign: TextAlign.center,
              decoration: const InputDecoration(
                hintText: 'Enter a new path here',
              ),
            ),
            TextButton(
              onPressed: () {
                _paths = [
                  ..._paths.map((p) => p.activated()),
                  BreadCrumbPath(
                    title: _textController.text,
                    isActive: false,
                  ),
                ];
                _pathsController.add(_paths);
                _textController.clear();
              },
              child: const Center(
                child: Text('Add new path'),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

Future<void> showBreadCrumbPathTappedDialog(
  BuildContext context,
  BreadCrumbPath path,
) {
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        content: Text('You tapped on $path'),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(context).pop();
            },
            child: const Text('OK'),
          ),
        ],
      );
    },
  );
}

Unique Map Values in Dart



import 'dart:developer' as devtools show log;

extension ContainsDuplicateValues on Map {
  bool get containsDuplicateValues => 
    {...values}.length != values.length;
}

extension Log on Object {
  void log() => devtools.log(toString());
}

const people1 = {
  1: 'Foo',
  2: 'Bar',
};
const people2 = {
  1: 'Foo',
  2: 'Foo',
};

void testIt() {
  people1.containsDuplicateValues.log(); // false
  people2.containsDuplicateValues.log(); // true
}

Smart Quotes/Dashes in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Smart Quotes/Dashes in Flutter'),
      ),
      body: const Padding(
        padding: EdgeInsets.all(16.0),
        child: TextField(
          smartQuotesType: SmartQuotesType.disabled,
          smartDashesType: SmartDashesType.disabled,
          maxLines: null,
        ),
      ),
    );
  }
}

Haptic Feedback in Flutter



class CenteredTight extends StatelessWidget {
  final Widget child;
  const CenteredTight({
    Key? key,
    required this.child,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [child],
    );
  }
}

class FullscreenImage extends StatefulWidget {
  final String imageUrl;
  const FullscreenImage({Key? key, required this.imageUrl}) : super(key: key);

  @override
  State<FullscreenImage> createState() => _FullscreenImageState();
}

class _FullscreenImageState extends State<FullscreenImage> {
  var shouldDisplayAppbar = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: shouldDisplayAppbar ? AppBar(title: const Text('Image')) : null,
      body: GestureDetector(
        onTap: () {
          setState(() => shouldDisplayAppbar = !shouldDisplayAppbar);
        },
        child: Image.network(
          widget.imageUrl,
          alignment: Alignment.center,
          width: double.infinity,
          height: double.infinity,
          fit: BoxFit.cover,
        ),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Haptic Feedback in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: CenteredTight(
          child: FractionallySizedBox(
            heightFactor: 0.7,
            child: GestureDetector(
              onLongPress: () async {
                await HapticFeedback.lightImpact();
                Navigator.of(context).push(
                  MaterialPageRoute(
                    builder: (context) {
                      return const FullscreenImage(
                        imageUrl: imageUrl,
                      );
                    },
                  ),
                );
              },
              child: Image.network(imageUrl),
            ),
          ),
        ),
      ),
    );
  }
}

Localization Delegates in Flutter



import 'package:flutter_gen/gen_l10n/app_localizations.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(
    MaterialApp(
      localizationsDelegates: AppLocalizations.localizationsDelegates,
      supportedLocales: AppLocalizations.supportedLocales,
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: BlocProvider<AuthBloc>(
        create: (context) => AuthBloc(FirebaseAuthProvider()),
        child: const HomePage(),
      ),
      routes: {
        createOrUpdateNoteRoute: (context) => const CreateUpdateNoteView(),
      },
    ),
  );
}

Extending Functions in Dart



import 'dart:developer' as devtools show log;

extension ToTextButton on VoidCallback {
  TextButton toTextButton(String title) {
    return TextButton(
      onPressed: this,
      child: Text(title),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Extensions in Flutter'),
      ),
      body: () {
        devtools.log('I am pressed');
      }.toTextButton('Press me'),
    );
  }
}

Paginated ListView in Flutter



@immutable
class Season {
  final String name;
  final String imageUrl;
  const Season({required this.name, required this.imageUrl});
  const Season.spring()
      : name = 'Spring',
        imageUrl = 'https://cnn.it/3xu58Ap';
  const Season.summer()
      : name = 'Summer',
        imageUrl = 'https://bit.ly/2VcCSow';
  const Season.autumn()
      : name = 'Autumn',
        imageUrl = 'https://bit.ly/3A3zStC';
  const Season.winter()
      : name = 'Winter',
        imageUrl = 'https://bit.ly/2TNY7wi';
}

const allSeasons = [
  Season.spring(),
  Season.summer(),
  Season.autumn(),
  Season.winter()
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    final width = MediaQuery.of(context).size.width;
    final height = width / (16.0 / 9.0);
    return Scaffold(
      appBar: AppBar(
        title: const Text('PageScrollPhysics in Flutter'),
      ),
      body: SizedBox(
        width: width,
        height: height,
        child: ListView(
          shrinkWrap: true,
          scrollDirection: Axis.horizontal,
          physics: const PageScrollPhysics(),
          clipBehavior: Clip.antiAlias,
          children: allSeasons.map((season) {
            return SizedBox(
              width: width,
              height: height,
              child: Image.network(
                season.imageUrl,
                height: height,
                fit: BoxFit.cover,
              ),
            );
          }).toList(),
        ),
      ),
    );
  }
}

Immutable Classes in Dart



import 'package:flutter/foundation.dart' show immutable;

@immutable
abstract class Animal {
  final String name;
  const Animal(this.name);
}

class Cat extends Animal {
  const Cat() : super('Cindy Clawford');
}

class Dog extends Animal {
  int age;
  Dog()
      : age = 0,
        super('Bark Twain');
}

Card Widget in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Card in Flutter'),
      ),
      body: Image.network(
        'https://bit.ly/36fNNj9',
        frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
          return Card(
            child: child,
            clipBehavior: Clip.antiAlias,
          );
        },
        loadingBuilder: (context, child, loadingProgress) {
          final totalBytes = loadingProgress?.expectedTotalBytes;
          final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
          if (totalBytes != null && bytesLoaded != null) {
            return Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: const [CircularProgressIndicator()],
            );
          } else {
            return child;
          }
        },
      ),
    );
  }
}

List Equality Ignoring Ordering in Dart



@immutable
class Person {
  final String name;
  const Person(this.name);

  @override
  bool operator ==(covariant Person other) => other.name == name;

  @override
  int get hashCode => name.hashCode;

  @override
  String toString() => name;
}

const people1 = [Person('Foo'), Person('Bar'), Person('Baz')];
const people2 = [Person('Foo'), Person('Bar'), Person('Baz')];
const people3 = [Person('Bar'), Person('Bar'), Person('Baz')];
const people4 = [Person('Bar'), Person('Baz')];

extension IsEqualToIgnoringOrdering<T> on List<T> {
  bool isEqualToIgnoringOrdering(List<T> other) =>
      length == other.length &&
      {...this}.intersection({...other}).length == length;
}

void testIt() {
  assert(people1.isEqualToIgnoringOrdering(people2));
  assert(!people1.isEqualToIgnoringOrdering(people3));
  assert(!people2.isEqualToIgnoringOrdering(people3));
  assert(!people3.isEqualToIgnoringOrdering(people4));
}

Shorten GitHub URLs in Dart

// Want to support my work 🀝? https://buymeacoffee.com/vandad

import 'dart:developer' as devtools show log;
import 'dart:convert' show utf8;

Future<Uri> shortenGitHubUrl(String longUrl) =>
    HttpClient().postUrl(Uri.parse('https://git.io/')).then((req) {
      req.add(utf8.encode('url=$longUrl'));
      return req.close();
    }).then(
      (resp) async {
        try {
          final location = resp.headers[HttpHeaders.locationHeader]?.first;
          if (location != null) {
            return Uri.parse(location);
          } else {
            throw 'No location was specified';
          }
        } catch (e) {
          return Uri.parse(longUrl);
        }
      },
    );

void testIt() async {
  final uri = await shortenGitHubUrl(
      'https://github.com/vandadnp/flutter-tips-and-tricks');
  devtools.log(uri.toString());
  // logs https://git.io/JS5Fm
}

Time Picker in Flutter



class HomePage extends StatelessWidget {
  final timeOfDay = ValueNotifier<TimeOfDay?>(null);
  HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder(
      valueListenable: timeOfDay,
      builder: (context, value, child) {
        final title = timeOfDay.value?.toString() ?? 'Time Picker in Flutter';
        return Scaffold(
          appBar: AppBar(title: Text(title)),
          body: Center(
            child: TextButton(
              onPressed: () async {
                timeOfDay.value = await showTimePicker(
                  context: context,
                  initialTime: TimeOfDay.now(),
                  initialEntryMode: TimePickerEntryMode.input,
                );
              },
              child: const Text('Please Pick a time'),
            ),
          ),
        );
      },
    );
  }
}

Throttled Print in Flutter



Stream<String> getStream() => Stream.periodic(
      const Duration(milliseconds: 100),
      (e) => DateTime.now().toString(),
    );

void testIt() async {
  await for (final now in getStream()) {
    debugPrintThrottled(now);
  }
}

Map Equality in Dart



typedef Name = String;
typedef Age = int;

const Map<Name, Age> people1 = {
  'foo': 20,
  'bar': 30,
  'baz': 40,
};

const Map<Name, Age> people2 = {
  'baz': 40,
  'foo': 20,
  'bar': 30,
};

void testIt() {
  assert(mapEquals(people1, people2));
}

Unique Maps in Dart



import 'dart:developer' as devtools show log;

typedef Name = String;
typedef Age = int;

const Map<Name, Age> people = {
  'foo': 20,
  'bar': 30,
  'baz': 20,
};

extension Unique<K, V> on Map<K, V> {
  Map<K, V> unique() {
    Map<K, V> result = {};
    for (final value in {...values}) {
      final firstKey = keys.firstWhereOrNull((key) => this[key] == value);
      if (firstKey != null) {
        result[firstKey] = value;
      }
    }
    return result;
  }
}

void testIt() {
  final uniques = people.unique();
  devtools.log(uniques.toString());
  // prints: {foo: 20, bar: 30}
}

Raw Auto Complete in Flutter



const emailProviders = [
  'gmail.com',
  'hotmail.com',
  'yahoo.com',
];

const icons = [
  'https://bit.ly/3HsvvvB',
  'https://bit.ly/3n6GW4L',
  'https://bit.ly/3zf2RLy',
];

class EmailTextField extends StatefulWidget {
  const EmailTextField({Key? key}) : super(key: key);

  @override
  State<EmailTextField> createState() => _EmailTextFieldState();
}

class _EmailTextFieldState extends State<EmailTextField> {
  late final TextEditingController _controller;
  late final FocusNode _focus;

  @override
  Widget build(BuildContext context) {
    return RawAutocomplete<String>(
      textEditingController: _controller,
      focusNode: _focus,
      fieldViewBuilder: (_, controller, focusNode, onSubmitted) {
        return TextFormField(
          controller: controller,
          focusNode: focusNode,
          onFieldSubmitted: (value) {
            onSubmitted();
          },
        );
      },
      optionsBuilder: (textEditingValue) {
        final lastChar = textEditingValue.text.characters.last;
        if (lastChar == '@') {
          return emailProviders;
        } else {
          return [];
        }
      },
      optionsViewBuilder: (context, onSelected, options) {
        return OptionsList(
          onSelected: onSelected,
          options: options,
          controller: _controller,
        );
      },
    );
  }

  @override
  void initState() {
    _controller = TextEditingController();
    _focus = FocusNode();
    super.initState();
  }

  @override
  void dispose() {
    _focus.dispose();
    _controller.dispose();
    super.dispose();
  }
}

class OptionsList extends StatelessWidget {
  final Iterable<String> options;
  final AutocompleteOnSelected<String> onSelected;
  final TextEditingController controller;
  const OptionsList({
    Key? key,
    required this.onSelected,
    required this.options,
    required this.controller,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.topLeft,
      child: Material(
        child: SizedBox(
          height: 150,
          child: ListView.builder(
            padding: const EdgeInsets.all(0.0),
            itemCount: options.length,
            itemBuilder: (context, index) {
              final option = options.elementAt(index);
              return GestureDetector(
                onTap: () => onSelected(controller.text + option),
                child: ListTile(
                  horizontalTitleGap: 2.0,
                  leading: Image.network(
                    icons[index],
                    width: 24,
                    height: 24,
                  ),
                  title: Text(option),
                ),
              );
            },
          ),
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Raw Auto Complete in Flutter'),
      ),
      body: const Padding(
        padding: EdgeInsets.all(16.0),
        child: EmailTextField(),
      ),
    );
  }
}

Title on Object in Dart



import 'dart:developer' as devtools show log;

extension CapTitle on Object {
  String get capitalizedTitle {
    String str;
    if (this is Enum) {
      str = (this as Enum).name;
    } else {
      str = toString();
    }
    return str[0].toUpperCase() + str.substring(1);
  }
}

enum EmailProviders { gmail, yahoo, hotmail }

void testIt() {
  EmailProviders.values.map((p) => p.capitalizedTitle).forEach(devtools.log);
  // prints these:
  // Gmail
  // Yahoo
  // Hotmail
}

Compute in Flutter



import 'dart:developer' as devtools show log;
import 'dart:convert' show utf8, json;

@immutable
class Person {
  final String name;
  final int age;
  const Person(this.name, this.age);
  Person.fromJson(Map<String, dynamic> json)
      : name = json["name"] as String,
        age = json["age"] as int;
}

Future<Iterable<Person>> downloadAndParsePersons(Uri uri) => HttpClient()
    .getUrl(uri)
    .then((req) => req.close())
    .then((response) => response.transform(utf8.decoder).join())
    .then((jsonString) => json.decode(jsonString) as List<dynamic>)
    .then((json) => json.map((map) => Person.fromJson(map)));

void testIt() async {
  final persons = await compute(
    downloadAndParsePersons,
    Uri.parse('https://bit.ly/3Jjcw8R'),
  );
  devtools.log(persons.toString());
}

Filter on Map in Dart



import 'dart:developer' as devtools show log;

typedef Name = String;
typedef Age = int;

extension Filter<K, V> on Map<K, V> {
  Iterable<MapEntry<K, V>> filter(
    bool Function(MapEntry<K, V> entry) f,
  ) sync* {
    for (final entry in entries) {
      if (f(entry)) {
        yield entry;
      }
    }
  }
}

const Map<Name, Age> people = {
  'foo': 20,
  'bar': 31,
  'baz': 25,
  'qux': 32,
};

void testIt() async {
  final peopleOver30 = people.filter((e) => e.value > 30);
  devtools.log(peopleOver30.toString());
  // ☝🏻 prints (MapEntry(bar: 31), MapEntry(qux: 32))
}

Type Alias in Dart



const Map<String, int> people1 = {
  'foo': 20,
  'bar': 30,
  'baz': 25,
};

typedef Age = int;

const Map<String, Age> people2 = {
  'foo': 20,
  'bar': 30,
  'baz': 25,
};

ValueNotifier in Flutter



class DynamicToolTipTextField extends StatelessWidget {
  final TextInputType? keyboardType;
  final ValueNotifier<String?> hint;
  final TextEditingController controller;
  const DynamicToolTipTextField({
    Key? key,
    required this.hint,
    required this.controller,
    this.keyboardType,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder(
      valueListenable: hint,
      builder: (context, value, child) {
        return TextField(
          keyboardType: keyboardType,
          controller: controller,
          decoration: InputDecoration(
            hintText: value as String?,
          ),
        );
      },
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

@immutable
abstract class HasText {
  String get text;
}

enum Hint { pleaseEnterYourEmail, youForgotToEnterYourEmail }

extension GetText on Hint {
  String get text {
    switch (this) {
      case Hint.pleaseEnterYourEmail:
        return 'Please enter your email';
      case Hint.youForgotToEnterYourEmail:
        return 'You forgot to enter your email';
    }
  }
}

class _HomePageState extends State<HomePage> {
  late final ValueNotifier<String?> _hint;
  late final TextEditingController _controller;

  @override
  void initState() {
    _hint = ValueNotifier<String?>(Hint.pleaseEnterYourEmail.text);
    _controller = TextEditingController();
    super.initState();
  }

  @override
  void dispose() {
    _hint.dispose();
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('ValueNotifier in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            DynamicToolTipTextField(
              hint: _hint,
              controller: _controller,
              keyboardType: TextInputType.emailAddress,
            ),
            TextButton(
              onPressed: () async {
                final email = _controller.text;
                if (email.trim().isEmpty) {
                  _hint.value = Hint.youForgotToEnterYourEmail.text;
                  await Future.delayed(const Duration(seconds: 2));
                  _hint.value = Hint.pleaseEnterYourEmail.text;
                }
              },
              child: const Text('Log in'),
            )
          ],
        ),
      ),
    );
  }
}

Object to Integer in Dart



enum ToIntStrategy { round, floor, ceil }

typedef ToIntOnErrorHandler = int Function(Object e);

extension ToInt on Object {
  int toInteger({
    ToIntStrategy strategy = ToIntStrategy.round,
    ToIntOnErrorHandler? onError,
  }) {
    try {
      final doubleValue = double.parse(toString());
      switch (strategy) {
        case ToIntStrategy.round:
          return doubleValue.round();
        case ToIntStrategy.floor:
          return doubleValue.floor();
        case ToIntStrategy.ceil:
          return doubleValue.ceil();
      }
    } catch (e) {
      if (onError != null) {
        return onError(e);
      } else {
        return -1;
      }
    }
  }
}

void testIt() {
  assert('xyz'.toInteger(onError: (_) => 100) == 100);
  assert(1.5.toInteger() == 2);
  assert(1.6.toInteger() == 2);
  assert('1.2'.toInteger(strategy: ToIntStrategy.floor) == 1);
  assert('1.2'.toInteger(strategy: ToIntStrategy.ceil) == 2);
  assert('1.5'.toInteger(strategy: ToIntStrategy.round) == 2);
}

Image Opacity in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _opacity;

  @override
  void initState() {
    _controller = AnimationController(
      vsync: this,
      duration: const Duration(seconds: 1),
    );
    _opacity = Tween(begin: 0.0, end: 1.0).animate(_controller);
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Image.network(
            'https://bit.ly/3ywI8l6',
            opacity: _opacity,
          ),
          Slider(
            value: _controller.value,
            onChanged: (value) {
              setState(() => _controller.value = value);
            },
          ),
        ],
      ),
    );
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }
}

Covariant in Dart

// Want to support my work 🀝? https://buymeacoffee.com/vandad

class Person {
  final String name;
  const Person(this.name);
  @override
  bool operator ==(Object other) {
    if (other is! Person) throw ArgumentError('Was expecting a person');
    return other.name == name;
  }

  @override
  int get hashCode => name.hashCode;
}

class Person {
  final String name;
  const Person(this.name);
  @override
  bool operator ==(covariant Person other) => other.name == name;

  @override
  int get hashCode => name.hashCode;
}

Custom Errors in Streams in Dart



class Either<V, E extends Exception> {
  final V? value;
  final E? error;

  const Either({this.value, this.error}) : assert((value ?? error) != null);

  bool get isError => error != null;
  bool get isValue => value != null;

  @override
  String toString() {
    if (value != null) {
      return "Value: $value";
    } else if (error != null) {
      return "Error: $error";
    } else {
      return 'Unknown state';
    }
  }
}

class DateTimeException implements Exception {
  final String reason;
  const DateTimeException({required this.reason});
}

Stream<Either<DateTime, DateTimeException>> getDateTime() async* {
  var index = 0;
  while (true) {
    if (index % 2 == 0) {
      yield Either(value: DateTime.now());
    } else {
      yield const Either(
        error: DateTimeException(reason: 'Something is wrong!'),
      );
    }
    index += 1;
  }
}

void testIt() async {
  await for (final value in getDateTime()) {
    dev.log(value.toString());
  }
}

Shake Animation in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

const animationWidth = 10.0;

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final TextEditingController _textController;
  late final AnimationController _animationController;
  late final Animation<double> _offsetAnim;
  final defaultHintText = 'Please enter your email here 😊';
  var _hintText = '';

  @override
  void initState() {
    _hintText = defaultHintText;
    _textController = TextEditingController();
    _animationController = AnimationController(
      duration: const Duration(milliseconds: 370),
      vsync: this,
    );
    _offsetAnim = Tween(
      begin: 0.0,
      end: animationWidth,
    ).chain(CurveTween(curve: Curves.elasticIn)).animate(
          _animationController,
        )..addStatusListener(
        (status) {
          if (status == AnimationStatus.completed) {
            _animationController.reverse();
          }
        },
      );
    super.initState();
  }

  @override
  void dispose() {
    _textController.dispose();
    _animationController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Shake Animation in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            AnimatedBuilder(
              animation: _offsetAnim,
              builder: (context, child) {
                return Container(
                  margin: const EdgeInsets.symmetric(
                    horizontal: animationWidth,
                  ),
                  padding: EdgeInsets.only(
                    left: _offsetAnim.value + animationWidth,
                    right: animationWidth - _offsetAnim.value,
                  ),
                  child: TextField(
                    controller: _textController,
                    keyboardType: TextInputType.emailAddress,
                    decoration: InputDecoration(
                      hintText: _hintText,
                    ),
                  ),
                );
              },
            ),
            TextButton(
                onPressed: () async {
                  if (_textController.text.isEmpty) {
                    setState(() {
                      _hintText = 'You forgot to enter your email πŸ₯²';
                      _animationController.forward(from: 0.0);
                    });
                    await Future.delayed(const Duration(seconds: 3));
                    setState(() {
                      _hintText = defaultHintText;
                    });
                  }
                },
                child: const Text('Login'))
          ],
        ),
      ),
    );
  }
}

Throw Enums in Dart



import 'dart:developer' as dev show log;

enum Exceptions { invalidUserName, invalidPassword }

void thisMethodThrows() {
  throw Exceptions.invalidPassword;
}

void testIt() {
  try {
    thisMethodThrows();
  } on Exceptions catch (e) {
    switch (e) {
      case (Exceptions.invalidUserName):
        dev.log("Invalid user name");
        break;
      case (Exceptions.invalidPassword):
        dev.log("Invalid password");
        break;
    }
  }
}

Future Error Test in Flutter



import 'dart:developer' as dev show log;

@immutable
abstract class UserException implements Exception {}

class InvalidUserNameException extends UserException {}

class InvalidUserAgeException extends UserException {}

@immutable
class User {
  final String name;
  final int age;
  User({required this.name, required this.age}) {
    if (!name.contains(RegExp(r'^[a-z ]+$'))) {
      throw InvalidUserNameException();
    } else if (age < 0 || age > 130) {
      throw InvalidUserAgeException();
    }
  }
  const User.anonymous()
      : name = 'Anonymous User',
        age = 0;
}

Future<User> getAsyncUser() => Future.delayed(
      const Duration(seconds: 1),
      () => User(name: 'Foo', age: 20),
    );

void testIt() async {
  final user = await getAsyncUser()
      .catchError(
        handleInvalidUsernameException,
        test: (e) => e is InvalidUserNameException,
      )
      .catchError(
        handleInvalidAgeException,
        test: (e) => e is InvalidUserAgeException,
      );
  dev.log(user.toString());
}

User handleInvalidUsernameException(Object? e) {
  dev.log(e.toString());
  return const User.anonymous();
}

User handleInvalidAgeException(Object? e) {
  dev.log(e.toString());
  return const User.anonymous();
}

Generic URL Retrieval in Dart



import 'dart:developer' as dev show log;

typedef StatusCodeResultBuilder<T> = Future<T> Function(
  int statusCode,
  HttpClientResponse response,
);

extension Get on Uri {
  Future<T?> getBody<T>({
    StatusCodeResultBuilder<T>? statusBuilder,
    T Function(Object error)? onNetworkError,
  }) async {
    try {
      final apiCall = await HttpClient().getUrl(this);
      final response = await apiCall.close();
      final builder = statusBuilder;
      if (builder == null) {
        final data = await response.transform(convert.utf8.decoder).join();
        if (data is T) {
          return data as T?;
        } else {
          return null;
        }
      } else {
        final result = await builder(response.statusCode, response);
        return result;
      }
    } catch (e) {
      if (onNetworkError != null) {
        return onNetworkError(e);
      } else {
        return null;
      }
    }
  }
}

extension ToUri on String {
  Uri toUri() => Uri.parse(this);
}

const url = 'https://bit.ly/3EKWcLa';

void testIt() async {
  final json = await url.toUri().getBody<String>(
    statusBuilder: (statusCode, response) async {
      if (statusCode == 200) {
        return await response.transform(convert.utf8.decoder).join();
      } else {
        return "{'error': 'Unexpected status code $statusCode'}";
      }
    },
    onNetworkError: (error) {
      return "{'error': 'Got network error'}";
    },
  );
  if (json != null) {
    dev.log(json);
  }
}

Custom Error Widget in Flutter



class MyErrorWidget extends StatelessWidget {
  final String text;
  const MyErrorWidget({Key? key, required this.text}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SizedBox(
        width: MediaQuery.of(context).size.width,
        child: Padding(
          padding: const EdgeInsets.all(16.0),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.start,
            children: [
              Image.network('https://bit.ly/3gHlTCU'),
              Text(
                text,
                textAlign: TextAlign.center,
                style: const TextStyle(
                  color: Colors.red,
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

void main() {
  ErrorWidget.builder = (FlutterErrorDetails details) {
    bool isInDebugMode = false;
    assert(() {
      isInDebugMode = true;
      return true;
    }());
    final message = details.exception.toString();
    if (isInDebugMode) {
      return MyErrorWidget(text: message);
    } else {
      return Text(
        message,
        textAlign: TextAlign.center,
      );
    }
  };

  runApp(
    const MaterialApp(
      home: HomePage(),
      debugShowCheckedModeBanner: false,
    ),
  );
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Error Widget in Flutter'),
      ),
      body: Builder(
        builder: (context) {
          throw Exception(
              'Here is an exception that is caught by our custom Error Widget in Flutter');
        },
      ),
    );
  }
}

Handle Multiple Future Errors in Dart



import 'dart:developer' as dev show log;

Future<Iterable<T>> waitOn<T>(
  Iterable<Future<T>> futures,
  Function onError,
) async {
  List<T> result = [];
  for (final future in futures) {
    final value = await future.catchError(onError);
    result.add(value);
  }
  return result;
}

void testIt() async {
  final f1 = Future.error('First Error');
  final f2 = Future.delayed(const Duration(seconds: 2), () => 10);
  final f3 = Future.error('Second error');
  final f4 = Future.delayed(const Duration(seconds: 2), () => 'Hello world');
  final result = await waitOn([f1, f2, f3, f4], (error) => -1);
  dev.log(result.toString()); // [-1, 10, -1, Hello world]
}

Future Error Handling in Dart

import 'dart:developer' as dev show log;

extension OnError<T> on Future<T> {
  Future<T> onErrorJustReturn(T value) => catchError((_) => value);
}

Future<bool> isUserRegistered({required String email}) => HttpClient()
    .postUrl(Uri.parse('https://website'))
    .then((req) {
      req.headers.add('email', email);
      return req.close();
    })
    .then((resp) => resp.statusCode == 200)
    .onErrorJustReturn(false);

void testIt() async {
  final isFooRegistered = await isUserRegistered(email: 'foo@flutter.com');
  dev.log(isFooRegistered.toString());
}

String to Toast in Flutter



extension Toast on String {
  Future<void> showAsToast(BuildContext context,
      {required Duration duration}) async {
    final scaffold = ScaffoldMessenger.of(context);
    final controller = scaffold.showSnackBar(
      SnackBar(
        content: Text(this),
        backgroundColor: const Color(0xFF24283b),
        behavior: SnackBarBehavior.floating,
        elevation: 2.0,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(10),
        ),
      ),
    );
    await Future.delayed(duration);
    controller.close();
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: TextButton(
          onPressed: () => 'Hello, World!'.showAsToast(
            context,
            duration: const Duration(seconds: 2),
          ),
          child: const Text('Show the snackbar'),
        ),
      ),
    );
  }
}

Waiting in Dart



Future<void> wait(Duration d) async {
  await Future.delayed(d);
}

extension Wait on int {
  Future<void> get seconds => wait(Duration(seconds: this));
  Future<void> get minutes => wait(Duration(minutes: this));
}

void testIt() async {
  await 2.seconds;
  'After 2 seconds'.log();
  await 3.minutes;
  'After 3 minutes'.log();
}

extension Log on Object {
  void log() {
    dev.log(toString());
  }
}

Loading Dialog in Flutter



typedef CloseDialog = void Function();

CloseDialog showLoadingScreen({
  required BuildContext context,
  required String text,
}) {
  final dialog = AlertDialog(
    content: Column(
      mainAxisSize: MainAxisSize.min,
      children: [
        const CircularProgressIndicator(),
        const SizedBox(height: 10),
        Text(text),
      ],
    ),
  );
  showDialog(
    context: context,
    barrierDismissible: false,
    builder: (_) => dialog,
  );

  return () => Navigator.of(context).pop();
}

void testIt(BuildContext context) async {
  final closeDialog = showLoadingScreen(
    context: context,
    text: 'Loading data...',
  );
  await Future.delayed(const Duration(seconds: 2));
  closeDialog();
}

Compact Map on Map<K,V> in Dart



const foo = 'foo';
const bar = 'bar';
const baz = 'baz';

const namesAndAges = {
  foo: 20,
  bar: 25,
  baz: 18,
};

const acceptedNames = [
  foo,
  bar,
];

void testIt() {
  final acceptedAges = namesAndAges.compactMap(
    (e) => acceptedNames.contains(e.key) ? e.value : null,
  );
  acceptedAges.log(); // [20, 25]
}

extension CompactMap<T, E> on Map<T, E> {
  Iterable<V> compactMap<V>(V? Function(MapEntry<T, E>) f) sync* {
    for (final entry in entries) {
      final extracted = f(entry);
      if (extracted != null) {
        yield extracted;
      }
    }
  }
}

Query Parameters in Dart



import 'dart:developer' as devtools show log;

const host = 'freecurrencyapi.net';
const path = '/api/v2/latest';
const apiKey = 'YOUR_API_KEY';
const baseCurrency = 'sek';
const params = {
  'apiKey': apiKey,
  'base_currency': 'sek',
};

void insteadOfThis() {
  const url = 'https://$host$path?apiKey=$apiKey&base_currency=$baseCurrency';
  url.log();
}

void doThis() {
  final url = Uri.https(host, path, params);
  url.log();
}

extension Log on Object {
  void log() {
    devtools.log(toString());
  }
}

Multiple Gradients in Container in Flutter



typedef GradientContainersBuilder = Map<LinearGradient, Widget?> Function();

class GradientContainers extends StatelessWidget {
  final GradientContainersBuilder builder;

  const GradientContainers({
    Key? key,
    required this.builder,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: builder().entries.map((mapEntry) {
        final gradient = mapEntry.key;
        final widget = mapEntry.value;
        return GradientContainer(
          gradient: gradient,
          child: widget,
        );
      }).toList(),
    );
  }
}

class GradientContainer extends StatelessWidget {
  final LinearGradient gradient;
  final Widget? child;

  const GradientContainer({Key? key, required this.gradient, this.child})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Positioned.fill(
      child: Container(
        decoration: BoxDecoration(
          gradient: gradient,
        ),
        child: child,
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GradientContainers(
        builder: () => {
          topLeftToBottomRightGradient: null,
          rightToLeftGradient: null,
          leftToRightGradinet: null,
          bottomRightGradient: Image.network('https://bit.ly/3otHHog'),
        },
      ),
    );
  }
}

const transparent = Color(0x00FFFFFF);

const topLeftToBottomRightGradient = LinearGradient(
  begin: Alignment.topLeft,
  end: Alignment.bottomRight,
  colors: [
    Color(0xff2ac3de),
    transparent,
  ],
);

const bottomRightGradient = LinearGradient(
  begin: Alignment.bottomRight,
  end: Alignment.topLeft,
  colors: [
    Color(0xffbb9af7),
    transparent,
  ],
);

const rightToLeftGradient = LinearGradient(
  begin: Alignment.centerRight,
  end: Alignment.centerLeft,
  colors: [
    Color(0xff9ece6a),
    transparent,
  ],
);

const leftToRightGradinet = LinearGradient(
  begin: Alignment.centerLeft,
  end: Alignment.centerRight,
  colors: [
    Color(0xff7dcfff),
    transparent,
  ],
);

void main() {
  runApp(
    const MaterialApp(
      home: HomePage(),
      debugShowCheckedModeBanner: false,
    ),
  );
}

Filter on Stream<List<T>> in Dart



import 'dart:developer' as devtools show log;

extension Filter<T> on Stream<List<T>> {
  Stream<List<T>> filter(bool Function(T) where) =>
      map((items) => items.where(where).toList());
}

final Stream<List<int>> allNumbers = Stream.periodic(
  const Duration(seconds: 1),
  (value) => [for (var i = 0; i < value; i++) i],
);

bool isEven(num value) => value % 2 == 0;
bool isOdd(num value) => value % 2 != 0;

extension EvenOdd<E extends num> on Stream<List<E>> {
  Stream<List<E>> get evenNumbers => filter(isEven);
  Stream<List<E>> get oddNumbers => filter(isOdd);
}

void readEvenNumbers() async {
  await for (final evenNumber in allNumbers.evenNumbers) {
    devtools.log('All even numbers: $evenNumber');
  }
}

void readOddNumbers() async {
  await for (final oddNumber in allNumbers.oddNumbers) {
    devtools.log('All odd numbers: $oddNumber');
  }
}

Generic Route Arguments in Flutter

extension GetArgument on BuildContext {
  T? getArgument<T>() {
    final modalRoute = ModalRoute.of(this);
    if (modalRoute != null) {
      final args = modalRoute.settings.arguments;
      if (args != null && args is T) {
        return args as T;
      }
    }
    return null;
  }
}

Generic Dialog in Flutter

typedef DialogOptionBuilder<T> = Map<String, T> Function();

Future<T?> showGenericDialog<T>({
  required BuildContext context,
  required String title,
  required String content,
  required DialogOptionBuilder optionsBuilder,
}) {
  final options = optionsBuilder();
  return showDialog<T>(
    context: context,
    builder: (context) {
      return AlertDialog(
        title: Text(title),
        content: Text(content),
        actions: options.keys.map(
          (optionTitle) {
            final T value = options[optionTitle];
            return TextButton(
              onPressed: () {
                Navigator.of(context).pop(value);
              },
              child: Text(optionTitle),
            );
          },
        ).toList(),
      );
    },
  );
}

Future<bool> showLogOutDialog(BuildContext context) {
  return showGenericDialog<bool>(
    context: context,
    title: 'Log out',
    content: 'Are you sure you want to log out?',
    optionsBuilder: () => {
      'Cancel': false,
      'Log out': true,
    },
  ).then(
    (value) => value ?? false,
  );
}

GitHub API in Flutter



import 'dart:io' show HttpHeaders, HttpClient;
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'dart:convert' show utf8, json;

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Future<Iterable<GithubUser>> getGithubFollowers(String accessToken) =>
    HttpClient()
        .getUrl(Uri.parse('https://api.github.com/user/followers'))
        .then((req) {
          req.headers
            ..set(HttpHeaders.authorizationHeader, 'Bearer $accessToken')
            ..set(HttpHeaders.contentTypeHeader, 'application/json');
          return req.close();
        })
        .then((resp) => resp.transform(utf8.decoder).join())
        .then((jsonStr) => json.decode(jsonStr) as List<dynamic>)
        .then(
          (jsonArray) => jsonArray.compactMap((element) {
            if (element is Map<String, dynamic>) {
              return element;
            } else {
              return null;
            }
          }),
        )
        .then(
          (listOfMaps) => listOfMaps.map(
            (map) => GithubUser.fromJson(map),
          ),
        );

class GithubUser {
  final String username;
  final String avatarUrl;

  GithubUser.fromJson(Map<String, dynamic> json)
      : username = json['login'] as String,
        avatarUrl = json['avatar_url'] as String;
}

extension CompactMap<T> on List<T> {
  List<E> compactMap<E>(E? Function(T element) f) {
    Iterable<E> imp(E? Function(T element) f) sync* {
      for (final value in this) {
        final mapped = f(value);
        if (mapped != null) {
          yield mapped;
        }
      }
    }

    return imp(f).toList();
  }
}

const token = 'PUT_YOUR_TOKEN_HERE';

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('GitHub API in Flutter'),
      ),
      body: FutureBuilder(
        future: getGithubFollowers(token),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.done:
              final users = (snapshot.data as Iterable<GithubUser>).toList();
              return ListView.builder(
                itemCount: users.length,
                itemBuilder: (context, index) {
                  final user = users[index];
                  return ListTile(
                    title: Text(user.username),
                    leading: CircularAvatar(url: user.avatarUrl),
                  );
                },
              );
            default:
              return const CircularProgressIndicator();
          }
        },
      ),
    );
  }
}

void main() {
  runApp(
    const MaterialApp(
      home: HomePage(),
      debugShowCheckedModeBanner: false,
    ),
  );
}

ChangeNotifier in Flutter



import 'package:provider/provider.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const allImages = [
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class ImageData {
  final Uint8List imageData;
  const ImageData(this.imageData);
}

class Images extends ChangeNotifier {
  final List<ImageData> _items = [];

  var _isLoading = false;
  bool get isLoading => _isLoading;

  UnmodifiableListView<ImageData> get items => UnmodifiableListView(_items);

  void loadNextImage() async {
    if (_items.length < allImages.length) {
      // time to load more
      _isLoading = true;
      notifyListeners();
      final imageUrl = allImages[_items.length];
      final networkAsset = NetworkAssetBundle(Uri.parse(imageUrl));
      final loaded = await networkAsset.load(imageUrl);
      final bytes = loaded.buffer.asUint8List();
      final imageData = ImageData(bytes);
      _items.insert(0, imageData);
      _isLoading = false;
      notifyListeners();
    } else {
      if (isLoading) {
        _isLoading = false;
        notifyListeners();
      }
    }
  }
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('ChangeNotifier in Flutter'),
        actions: [
          Consumer<Images>(
            builder: (context, value, child) {
              return IconButton(
                onPressed: () {
                  value.loadNextImage();
                },
                icon: const Icon(Icons.add_box_outlined),
              );
            },
          )
        ],
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Consumer<Images>(
          builder: (context, value, child) {
            final images = value.items;
            final isLoading = value.isLoading;
            return ListView.builder(
              itemBuilder: (context, index) {
                if (index == 0 && isLoading) {
                  return Center(
                    child: Column(
                      children: const [
                        CircularProgressIndicator(),
                        SizedBox(height: 16.0),
                      ],
                    ),
                  );
                } else {
                  final imageIndex = isLoading ? index - 1 : index;
                  final imageData = images[imageIndex].imageData;
                  return Column(
                    children: [
                      RoundedImageWithShadow(imageData: imageData),
                      const SizedBox(height: 16.0),
                    ],
                  );
                }
              },
              itemCount: isLoading ? images.length + 1 : images.length,
            );
          },
        ),
      ),
    );
  }
}

class RoundedImageWithShadow extends StatelessWidget {
  final Uint8List imageData;
  const RoundedImageWithShadow({Key? key, required this.imageData})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            blurRadius: 2,
            color: Colors.black.withAlpha(40),
            spreadRadius: 2,
          ),
        ],
      ),
      child: Image.memory(
        imageData,
        fit: BoxFit.cover,
      ),
    );
  }
}

void main() {
  runApp(
    MaterialApp(
      home: ChangeNotifierProvider(
        create: (_) => Images(),
        child: const HomePage(),
      ),
      debugShowCheckedModeBanner: false,
    ),
  );
}

Refresh Indicator in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const allImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final _images = [allImages.first];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Refresh Indicator in Flutter'),
      ),
      body: RefreshIndicator(
        onRefresh: () async {
          final nextIndex = _images.length + 1;
          if (nextIndex < allImages.length) {
            setState(() {
              _images.insert(0, allImages[nextIndex]);
            });
          }
        },
        child: ListView.builder(
          physics: const AlwaysScrollableScrollPhysics(),
          padding: const EdgeInsets.all(16),
          itemCount: _images.length,
          itemBuilder: (context, index) {
            final imageUrl = _images[index];
            return Column(
              children: [
                RoundedImageWithShadow(url: imageUrl),
                const SizedBox(height: 16),
              ],
            );
          },
        ),
      ),
    );
  }
}

class RoundedImageWithShadow extends StatelessWidget {
  final String url;
  const RoundedImageWithShadow({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            blurRadius: 2,
            color: Colors.black.withAlpha(40),
            spreadRadius: 2,
          ),
        ],
      ),
      child: Image.network(url),
    );
  }
}

FlatMap in Dart



extension FlatMap<T> on T? {
  E? flatMap<E>(E? Function(T) f) => this != null ? f(this!) : null;
}

AuthUser? get insteadOfThis {
  final user = FirebaseAuth.instance.currentUser;
  if (user != null) {
    return AuthUser.fromFirebase(user);
  } else {
    return null;
  }
}

AuthUser? get doThis =>
    FirebaseAuth.instance.currentUser.flatMap((u) => AuthUser.fromFirebase(u));

OrientationBuilder in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class RoundedImageWithShadow extends StatelessWidget {
  final String url;
  const RoundedImageWithShadow({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        boxShadow: [
          BoxShadow(
            blurRadius: 2,
            color: Colors.black.withAlpha(40),
            spreadRadius: 2,
          ),
        ],
      ),
      child: Image.network(url),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: OrientationBuilder(
          builder: (context, orientation) {
            final int count;
            switch (orientation) {
              case Orientation.portrait:
                count = 2;
                break;
              case Orientation.landscape:
                count = 4;
                break;
            }
            return GridView.count(
              padding: const EdgeInsets.all(8.0),
              crossAxisCount: count,
              mainAxisSpacing: 8.0,
              crossAxisSpacing: 8.0,
              children: images
                  .map((url) => RoundedImageWithShadow(url: url))
                  .toList(),
            );
          },
        ),
      ),
    );
  }
}

final images = [
  'https://bit.ly/3qJ2FCf',
  'https://bit.ly/3Hs9JsV',
  'https://bit.ly/3cfT6Cv',
  'https://bit.ly/30wGnIE',
  'https://bit.ly/3kJYsum',
  'https://bit.ly/3oDoMaJ',
  'https://bit.ly/3FndXQM',
  'https://bit.ly/3ci4i1f',
];

Linear Gradient in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Linear Gradient in Flutter'),
      ),
      body: const ImageWithShadow(url: 'https://bit.ly/3otHHog'),
    );
  }
}

class ImageWithShadow extends StatelessWidget {
  final String url;

  const ImageWithShadow({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: Stack(
        children: [
          Positioned.fill(
            child: Container(
              decoration: BoxDecoration(
                boxShadow: [
                  BoxShadow(
                    blurRadius: 10.0,
                    color: Colors.black.withOpacity(0.5),
                    offset: const Offset(0.0, 3.0),
                  )
                ],
                borderRadius: const BorderRadius.all(Radius.circular(20)),
                gradient: const LinearGradient(
                  begin: Alignment.topCenter,
                  end: Alignment.bottomCenter,
                  colors: [
                    Color.fromARGB(255, 176, 229, 251),
                    Color.fromARGB(255, 235, 202, 250)
                  ],
                ),
              ),
            ),
          ),
          Image.network(url),
        ],
      ),
    );
  }
}

Bloc Text Editing Controller in Flutter

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:bloc/bloc.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

abstract class Event {
  const Event();
}

class SearchEvent extends Event {
  final String searchString;
  const SearchEvent(this.searchString);
}

class ClearSearch extends Event {}

class SearchBloc extends Bloc<Event, List<String>> {
  static const names = ['foo', 'bar', 'baz'];

  SearchBloc() : super(names) {
    on<Event>((event, emit) {
      if (event is SearchEvent) {
        emit(names
            .where((element) => element.contains(event.searchString))
            .toList());
      } else if (event is ClearSearch) {
        emit(names);
      }
    });
  }
}

class BlocTextEditingController extends TextEditingController {
  SearchBloc? bloc;
  BlocTextEditingController() {
    addListener(() {
      if (text.isEmpty) {
        bloc?.add(ClearSearch());
      } else {
        bloc?.add(SearchEvent(text));
      }
    });
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

const largeStyle = TextStyle(fontSize: 30);

class _HomePageState extends State<HomePage> {
  late final BlocTextEditingController _controller;

  @override
  void initState() {
    _controller = BlocTextEditingController();
    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.bloc = BlocProvider.of<SearchBloc>(context);
    return Scaffold(
      appBar: AppBar(
        title: Text('Bloc Search in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: BlocBuilder<SearchBloc, List<String>>(
          builder: (context, state) {
            return ListView.builder(
              itemBuilder: (context, index) {
                if (index == 0) {
                  // search field
                  return TextField(
                    decoration: InputDecoration(
                      hintText: 'Enter search term here...',
                      hintStyle: largeStyle,
                    ),
                    style: largeStyle,
                    controller: _controller,
                  );
                } else {
                  final name = state[index - 1];
                  return ListTile(
                    title: Text(
                      name,
                      style: largeStyle,
                    ),
                  );
                }
              },
              itemCount: state.length + 1, // +1 for search
            );
          },
        ),
      ),
    );
  }
}

Blurred TabBar in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class CustomTabBar extends StatelessWidget {
  final List<IconButton> buttons;

  const CustomTabBar({Key? key, required this.buttons}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.bottomCenter,
      child: ClipRect(
        child: Container(
          height: 80,
          color: Colors.white.withOpacity(0.4),
          child: BackdropFilter(
            filter: ImageFilter.blur(sigmaX: 4.0, sigmaY: 4.0),
            child: Container(
              width: double.infinity,
              decoration: BoxDecoration(
                color: Colors.white.withOpacity(0.5),
              ),
              child: Padding(
                padding: const EdgeInsets.only(bottom: 15),
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  mainAxisAlignment: MainAxisAlignment.spaceAround,
                  children: buttons,
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

const summerIcon = Icon(
  Icons.surfing,
  size: 40.0,
  color: Colors.teal,
);

const autumnIcon = Icon(
  Icons.nature_outlined,
  size: 40.0,
  color: Colors.black45,
);

const winterIcon = Icon(
  Icons.snowboarding,
  size: 40.0,
  color: Colors.black45,
);

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Blurred Tab Bar'),
      ),
      body: Stack(
        children: [
          ListView.builder(
            itemCount: images.length,
            itemBuilder: (context, index) {
              final url = images[index];
              return Image.network(url);
            },
          ),
          CustomTabBar(
            buttons: [
              IconButton(
                icon: summerIcon,
                onPressed: () {
                  // implement me
                },
              ),
              IconButton(
                icon: autumnIcon,
                onPressed: () {
                  // implement me
                },
              ),
              IconButton(
                icon: winterIcon,
                onPressed: () {
                  // implement me
                },
              )
            ],
          )
        ],
      ),
    );
  }
}

Play YouTube in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

const videoIds = [
  'BHACKCNDMW8',
  '26h9hBZFl7w',
  'glENND73k4Q',
  'd0tU18Ybcvk',
];

class VideoView extends StatelessWidget {
  final String videoId;
  final _key = UniqueKey();

  VideoView({required this.videoId});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Watch a Video'),
      ),
      body: Center(
        child: Container(
          height: 232.0,
          child: WebView(
            key: _key,
            initialUrl: 'https://www.youtube.com/embed/$videoId',
            javascriptMode: JavascriptMode.unrestricted,
          ),
        ),
      ),
    );
  }
}

class YouTubeVideoThumbnail extends StatelessWidget {
  final String videoId;
  final String thumbnailUrl;

  const YouTubeVideoThumbnail({Key? key, required this.videoId})
      : thumbnailUrl = 'https://img.youtube.com/vi/$videoId/maxresdefault.jpg',
        super(key: key);

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () {
        Navigator.of(context).push(
          MaterialPageRoute(
            builder: (_) => VideoView(videoId: videoId),
          ),
        );
      },
      child: Container(
        height: 256.0,
        clipBehavior: Clip.antiAlias,
        decoration: BoxDecoration(
          boxShadow: [
            BoxShadow(
              blurRadius: 10.0,
              color: Colors.black.withAlpha(50),
              spreadRadius: 10.0,
            ),
          ],
          borderRadius: BorderRadius.circular(20),
          image: DecorationImage(
            fit: BoxFit.fitHeight,
            image: NetworkImage(thumbnailUrl),
          ),
        ),
        child: Center(
          child: Icon(
            Icons.play_arrow,
            color: Colors.white,
            size: 100.0,
          ),
        ),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('YouTube Videos in Flutter')),
      body: ListView.builder(
        itemCount: videoIds.length,
        itemBuilder: (context, index) {
          final videoId = videoIds[index];
          return Padding(
            padding: const EdgeInsets.all(8.0),
            child: YouTubeVideoThumbnail(videoId: videoId),
          );
        },
      ),
    );
  }
}

ListView Background in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class ListItem {
  const ListItem();
  factory ListItem.emptyTile() => EmptyTile();
  factory ListItem.tile(
    String title,
    String subTitle,
  ) =>
      Tile(
        title,
        subTitle,
      );
}

class Tile extends ListItem {
  final String title;
  final String subTitle;
  const Tile(this.title, this.subTitle) : super();
}

class EmptyTile extends ListItem {}

final items = [
  for (var i = 1; i <= 6; i++) ListItem.tile('Title $i', 'Sub title $i'),
  ListItem.emptyTile(),
  for (var i = 7; i <= 12; i++) ListItem.tile('Title $i', 'Sub title $i'),
];

class Background extends StatelessWidget {
  final Widget child;
  const Background({Key? key, required this.child}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20),
        image: DecorationImage(
          fit: BoxFit.fitHeight,
          image: NetworkImage('https://bit.ly/3jXSDto'),
        ),
      ),
      child: child,
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Background(
        child: ListView.builder(
          padding: EdgeInsets.zero,
          itemCount: items.length,
          itemBuilder: (context, index) {
            final item = items[index];
            if (item is Tile) {
              return Container(
                color: Colors.grey[200],
                child: ListTile(
                  title: Text(item.title),
                  subtitle: Text(item.subTitle),
                ),
              );
            } else if (item is EmptyTile) {
              return SizedBox(
                height: 450,
              );
            } else {
              throw 'unexpcted item';
            }
          },
        ),
      ),
    );
  }
}

Integer to Binary in Dart

extension ToBinary on int {
  String toBinary(
    int len, {
    int separateAtLength = 4,
    String separator = ',',
  }) =>
      toRadixString(2)
          .padLeft(len, '0')
          .splitByLength(separateAtLength)
          .join(separator);
}

void testIt() {
  assert(1.toBinary(8) == '0000,0001');
  assert(2.toBinary(4) == '0010');
  assert(3.toBinary(16) == '0000,0000,0000,0011');
  assert(255.toBinary(8, separateAtLength: 8) == '11111111');
  assert(255.toBinary(8, separateAtLength: 4) == '1111,1111');
}

extension SplitByLength on String {
  Iterable<String> splitByLength(int len, {String filler = '0'}) sync* {
    final missingFromLength =
        length % len == 0 ? 0 : len - (characters.length % len);
    final expectedLength = length + missingFromLength;
    final src = padLeft(expectedLength, filler);
    final chars = src.characters;
    for (var i = 0; i < chars.length; i += len) {
      yield chars.getRange(i, i + len).toString();
    }
  }
}

Split String by Length in Dart



void testIt() {
  assert('dartlang'
      .splitByLength(5, filler: 'πŸ’™')
      .isEqualTo(['πŸ’™πŸ’™dar', 'tlang']));

  assert('0100010'.splitByLength(4).isEqualTo(['0010', '0010']));
  assert('foobar'.splitByLength(3).isEqualTo(['foo', 'bar']));
  assert('flutter'.splitByLength(4, filler: 'X').isEqualTo(['Xflu', 'tter']));
  assert('dart'.splitByLength(5, filler: '').isEqualTo(['dart']));
}

extension SplitByLength on String {
  Iterable<String> splitByLength(int len, {String filler = '0'}) sync* {
    final missingFromLength =
        length % len == 0 ? 0 : len - (characters.length % len);
    final expectedLength = length + missingFromLength;
    final src = padLeft(expectedLength, filler);
    final chars = src.characters;
    for (var i = 0; i < chars.length; i += len) {
      yield chars.getRange(i, i + len).toString();
    }
  }
}

Image Tint in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

enum OverlayColor { brown, orange, yellow, green, blue }

extension Color on OverlayColor {
  MaterialColor get color {
    switch (this) {
      case OverlayColor.blue:
        return Colors.blue;
      case OverlayColor.brown:
        return Colors.brown;
      case OverlayColor.green:
        return Colors.green;
      case OverlayColor.orange:
        return Colors.orange;
      case OverlayColor.yellow:
        return Colors.yellow;
    }
  }
}

extension Title on OverlayColor {
  String get title => toString().split('.').last;
}

extension ToTextButtonWithValue on OverlayColor {
  TextButtonWithValue<OverlayColor> toTextButtonWithValue(
      OnTextButtonWithValuePressed onPressed) {
    return TextButtonWithValue(
      value: this,
      onPressed: onPressed,
      child: Text(title),
    );
  }
}

typedef OnTextButtonWithValuePressed<T> = void Function(T value);

class TextButtonWithValue<T> extends StatelessWidget {
  final T value;
  final OnTextButtonWithValuePressed onPressed;
  final Widget child;
  const TextButtonWithValue({
    Key? key,
    required this.value,
    required this.onPressed,
    required this.child,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        onPressed(value);
      },
      child: child,
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  OverlayColor? _overlayColor;

  ColorFilter? getcolorFilter() {
    final overlayColor = _overlayColor;
    if (overlayColor == null) {
      return null;
    }
    return ColorFilter.mode(
      overlayColor.color,
      BlendMode.colorBurn,
    );
  }

  Iterable<Widget> overlayColorButtons() {
    return OverlayColor.values.map((overlayColor) {
      return Expanded(
        flex: 1,
        child: Container(
          child: overlayColor.toTextButtonWithValue(
            (value) {
              setState(() {
                _overlayColor = value;
              });
            },
          ),
        ),
      );
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Tinting Images in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: [
            Container(
              height: 250.0,
              clipBehavior: Clip.antiAlias,
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(20),
                image: DecorationImage(
                  colorFilter: getcolorFilter(),
                  fit: BoxFit.fitHeight,
                  image: NetworkImage('https://bit.ly/3jOueGG'),
                ),
              ),
            ),
            SizedBox(height: 16.0),
            Row(
              children: overlayColorButtons().toList(),
            )
          ],
        ),
      ),
    );
  }
}

SlideTransition in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/gestures.dart';

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final _controller = AnimationController(
    duration: Duration(milliseconds: 500),
    vsync: this,
  );

  late final _animation = Tween<Offset>(
    begin: Offset(0.0, 0.0),
    end: Offset(-0.83, 0.0),
  ).animate(
    CurvedAnimation(
      parent: _controller,
      curve: Curves.easeInQuint,
    ),
  );

  var _isExpanded = false;

  @override
  void dispose() {
    super.dispose();
    _controller.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.forward();
    return Scaffold(
      body: SizedBox.expand(
        child: Stack(
          fit: StackFit.passthrough,
          children: [
            Image.network(
              'https://bit.ly/3BWYDbz',
              fit: BoxFit.fitHeight,
            ),
            Positioned(
              top: 200.0,
              child: SlideTransition(
                position: _animation,
                child: GestureDetector(
                  onTap: () {
                    _isExpanded = !_isExpanded;
                    if (_isExpanded) {
                      _controller.reverse();
                    } else {
                      _controller.forward();
                    }
                  },
                  child: Box(),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class Box extends StatelessWidget {
  const Box({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        color: Colors.blue[200]?.withAlpha(200),
        border: Border.all(
          color: Colors.blue,
          style: BorderStyle.solid,
          width: 1.0,
        ),
        borderRadius: BorderRadius.only(
          topRight: Radius.circular(10),
          bottomRight: Radius.circular(10),
        ),
      ),
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Row(
          children: [
            Text(
              'By: Jesper Anhede',
              style: TextStyle(
                fontSize: 18.0,
              ),
            ),
            SizedBox(width: 10.0),
            Icon(
              Icons.info,
              color: Colors.pink[400],
            ),
          ],
        ),
      ),
    );
  }
}

Expansion Panels and Lists in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class Event {
  final String title;
  final String details;
  final String imageUrl;
  bool isExpanded = false;

  Event({
    required this.title,
    required this.details,
    required this.imageUrl,
  });

  @override
  bool operator ==(covariant Event other) => title == other.title;
}

const diwaliDetails =
    '''Diwali, or Dipawali, is India's biggest and most important holiday of the year. The festival gets its name from the row (avali) of clay lamps (deepa) that Indians light outside their homes to symbolize the inner light that protects from spiritual darkness. This festival is as important to Hindus as the Christmas holiday is to Christians.''';

const halloweenDetails =
    '''Halloween or Hallowe'en, less commonly known as Allhalloween, All Hallows' Eve, or All Saints' Eve, is a celebration observed in many countries on 31 October, the eve of the Western Christian feast of All Hallows' Day.''';

final events = [
  Event(
    title: 'Diwali',
    details: diwaliDetails,
    imageUrl: 'https://bit.ly/3mGg8YW',
  ),
  Event(
    title: 'Halloween',
    details: halloweenDetails,
    imageUrl: 'https://bit.ly/3wb1w7j',
  ),
];

extension ToPanel on Event {
  ExpansionPanel toPanel() {
    return ExpansionPanel(
      headerBuilder: (context, isExpanded) {
        return Padding(
          padding: const EdgeInsets.all(8.0),
          child: Text(
            title,
            style: TextStyle(fontSize: 30.0),
          ),
        );
      },
      isExpanded: isExpanded,
      body: Container(
        height: 250,
        width: double.infinity,
        decoration: BoxDecoration(
          image: DecorationImage(
            fit: BoxFit.fitWidth,
            colorFilter: ColorFilter.mode(
              Colors.black.withOpacity(0.5),
              BlendMode.luminosity,
            ),
            image: NetworkImage(imageUrl),
          ),
        ),
        child: SingleChildScrollView(
          child: Padding(
            padding: const EdgeInsets.all(8.0),
            child: Text(
              details,
              textAlign: TextAlign.center,
              style: TextStyle(fontSize: 20, color: Colors.white, shadows: [
                Shadow(
                  blurRadius: 1.0,
                  offset: Offset.zero,
                  color: Colors.black,
                )
              ]),
            ),
          ),
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Expansion Panels in Flutter'),
      ),
      body: SingleChildScrollView(
        child: ExpansionPanelList(
          children: events.map((e) => e.toPanel()).toList(),
          expansionCallback: (panelIndex, isExpanded) {
            setState(() {
              events[panelIndex].isExpanded = !isExpanded;
            });
          },
        ),
      ),
    );
  }
}

Complete CRUD App in Flutter

//Want to support my work 🀝? https://buymeacoffee.com/vandad

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart'
    show getApplicationDocumentsDirectory;

class Person implements Comparable {
  final int id;
  final String firstName;
  final String lastName;
  const Person(this.id, this.firstName, this.lastName);

  String get fullName => '$firstName $lastName';

  Person.fromData(Map<String, Object?> data)
      : id = data['ID'] as int,
        firstName = data['FIRST_NAME'] as String,
        lastName = data['LAST_NAME'] as String;

  @override
  int compareTo(covariant Person other) => other.id.compareTo(id);

  @override
  bool operator ==(covariant Person other) => id == other.id;

  @override
  String toString() =>
      'Person, ID = $id, firstName = $firstName, lastName = $lastName';
}

class PersonDB {
  final _controller = StreamController<List<Person>>.broadcast();
  List<Person> _persons = [];
  Database? _db;
  final String dbName;
  PersonDB({required this.dbName});

  Future<bool> close() async {
    final db = _db;
    if (db == null) {
      return false;
    }
    await db.close();
    return true;
  }

  Future<bool> open() async {
    if (_db != null) {
      return true;
    }
    final directory = await getApplicationDocumentsDirectory();
    final path = '${directory.path}/$dbName';
    try {
      final db = await openDatabase(path);
      _db = db;

      // create the table if it doesn't exist

      final create = '''CREATE TABLE IF NOT EXISTS PEOPLE (
          ID INTEGER PRIMARY KEY AUTOINCREMENT,
          FIRST_NAME STRING NOT NULL,
          LAST_NAME STRING NOT NULL
        )''';

      await db.execute(create);

      // if everything went fine, we then read all the objects
      // and populate the stream

      _persons = await _fetchPeople();
      _controller.add(_persons);
      return true;
    } catch (e) {
      print('error = $e');
      return false;
    }
  }

  Future<List<Person>> _fetchPeople() async {
    final db = _db;
    if (db == null) {
      return [];
    }

    try {
      // read the existing data if any
      final readResult = await db.query(
        'PEOPLE',
        distinct: true,
        columns: ['ID', 'FIRST_NAME', 'LAST_NAME'],
        orderBy: 'ID',
      );

      final people = readResult.map((row) => Person.fromData(row)).toList();
      return people;
    } catch (e) {
      print('error = $e');
      return [];
    }
  }

  Future<bool> delete(Person person) async {
    final db = _db;
    if (db == null) {
      return false;
    }
    try {
      final deletedCount = await db.delete(
        'PEOPLE',
        where: 'ID = ?',
        whereArgs: [person.id],
      );

      // delete it locally as well

      if (deletedCount == 1) {
        _persons.remove(person);
        _controller.add(_persons);
        return true;
      } else {
        return false;
      }
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  Future<bool> create(String firstName, String lastName) async {
    final db = _db;
    if (db == null) {
      return false;
    }
    try {
      final id = await db.insert(
        'PEOPLE',
        {
          'FIRST_NAME': firstName,
          'LAST_NAME': lastName,
        },
      );

      final person = Person(id, firstName, lastName);
      _persons.add(person);
      _controller.add(_persons);

      return true;
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  // uses the person's id to update its first name and last name
  Future<bool> update(Person person) async {
    final db = _db;
    if (db == null) {
      return false;
    }
    try {
      final updatedCount = await db.update(
        'PEOPLE',
        {
          'FIRST_NAME': person.firstName,
          'LAST_NAME': person.lastName,
        },
        where: 'ID = ?',
        whereArgs: [person.id],
      );

      if (updatedCount == 1) {
        _persons.removeWhere((p) => p.id == person.id);
        _persons.add(person);
        _controller.add(_persons);
        return true;
      } else {
        return false;
      }
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  Stream<List<Person>> all() =>
      _controller.stream.map((event) => event..sort());
}

typedef OnCompose = void Function(String firstName, String lastName);

class ComposeWidget extends StatefulWidget {
  final OnCompose onCompose;

  const ComposeWidget({Key? key, required this.onCompose}) : super(key: key);

  @override
  State<ComposeWidget> createState() => _ComposeWidgetState();
}

class _ComposeWidgetState extends State<ComposeWidget> {
  final firstNameController = TextEditingController();
  final lastNameController = TextEditingController();

  @override
  void dispose() {
    firstNameController.dispose();
    lastNameController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Column(children: [
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter first name',
          ),
          controller: firstNameController,
        ),
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter last name',
          ),
          controller: lastNameController,
        ),
        TextButton(
          onPressed: () {
            final firstName = firstNameController.text;
            final lastName = lastNameController.text;
            widget.onCompose(firstName, lastName);
          },
          child: Text(
            'Add to list',
            style: TextStyle(fontSize: 24),
          ),
        ),
      ]),
    );
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  late final PersonDB _crudStorage;

  @override
  void initState() {
    _crudStorage = PersonDB(dbName: 'db.sqlite');
    _crudStorage.open();
    super.initState();
  }

  @override
  void dispose() {
    _crudStorage.close();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('SQLite in Flutter'),
      ),
      body: StreamBuilder(
        stream: _crudStorage.all(),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.active:
            case ConnectionState.waiting:
              if (snapshot.data == null) {
                return Center(child: CircularProgressIndicator());
              }
              final people = snapshot.data as List<Person>;
              return Column(
                children: [
                  ComposeWidget(
                    onCompose: (firstName, lastName) async {
                      await _crudStorage.create(firstName, lastName);
                    },
                  ),
                  Expanded(
                    child: ListView.builder(
                      itemCount: people.length,
                      itemBuilder: (context, index) {
                        final person = people[index];
                        return ListTile(
                          onTap: () async {
                            final update =
                                await showUpdateDialog(context, person);
                            if (update == null) {
                              return;
                            }
                            await _crudStorage.update(update);
                          },
                          title: Text(
                            person.fullName,
                            style: TextStyle(fontSize: 24),
                          ),
                          subtitle: Text(
                            'ID: ${person.id}',
                            style: TextStyle(fontSize: 18),
                          ),
                          trailing: TextButton(
                            onPressed: () async {
                              final shouldDelete =
                                  await showDeleteDialog(context);
                              if (shouldDelete) {
                                await _crudStorage.delete(person);
                              }
                            },
                            child: Icon(
                              Icons.disabled_by_default_rounded,
                              color: Colors.red,
                            ),
                          ),
                        );
                      },
                    ),
                  ),
                ],
              );
            default:
              return Center(child: CircularProgressIndicator());
          }
        },
      ),
    );
  }
}

final firstNameController = TextEditingController();
final lastNameController = TextEditingController();

Future<Person?> showUpdateDialog(BuildContext context, Person person) {
  firstNameController.text = person.firstName;
  lastNameController.text = person.lastName;
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        content: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text('Enter your udpated values here:'),
            TextField(controller: firstNameController),
            TextField(controller: lastNameController),
          ],
        ),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(context).pop(null);
            },
            child: Text('Cancel'),
          ),
          TextButton(
            onPressed: () {
              final newPerson = Person(
                person.id,
                firstNameController.text,
                lastNameController.text,
              );
              Navigator.of(context).pop(newPerson);
            },
            child: Text('Save'),
          ),
        ],
      );
    },
  ).then((value) {
    if (value is Person) {
      return value;
    } else {
      return null;
    }
  });
}

Future<bool> showDeleteDialog(BuildContext context) {
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        content: Text('Are you sure you want to delete this item?'),
        actions: [
          TextButton(
            onPressed: () {
              Navigator.of(context).pop(false);
            },
            child: Text('No'),
          ),
          TextButton(
            onPressed: () {
              Navigator.of(context).pop(true);
            },
            child: Text('Delete'),
          )
        ],
      );
    },
  ).then(
    (value) {
      if (value is bool) {
        return value;
      } else {
        return false;
      }
    },
  );
}

SQLite Storage in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path_provider/path_provider.dart'
    show getApplicationDocumentsDirectory;

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class Person implements Comparable {
  final int id;
  final String firstName;
  final String lastName;
  const Person(this.id, this.firstName, this.lastName);

  String get fullName => '$firstName $lastName';

  Person.fromData(Map<String, Object?> data)
      : id = data['ID'] as int,
        firstName = data['FIRST_NAME'] as String,
        lastName = data['LAST_NAME'] as String;

  @override
  int compareTo(covariant Person other) => other.id.compareTo(id);
}

typedef OnCompose = void Function(String firstName, String lastName);

class ComposeWidget extends StatefulWidget {
  final OnCompose onCompose;

  const ComposeWidget({Key? key, required this.onCompose}) : super(key: key);

  @override
  State<ComposeWidget> createState() => _ComposeWidgetState();
}

class _ComposeWidgetState extends State<ComposeWidget> {
  final firstNameController = TextEditingController();
  final lastNameController = TextEditingController();

  @override
  void dispose() {
    firstNameController.dispose();
    lastNameController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Column(children: [
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter first name',
          ),
          controller: firstNameController,
        ),
        TextField(
          style: TextStyle(fontSize: 24),
          decoration: InputDecoration(
            hintText: 'Enter last name',
          ),
          controller: lastNameController,
        ),
        TextButton(
          onPressed: () {
            final firstName = firstNameController.text;
            final lastName = lastNameController.text;
            widget.onCompose(firstName, lastName);
          },
          child: Text(
            'Add to list',
            style: TextStyle(fontSize: 24),
          ),
        ),
      ]),
    );
  }
}

class _HomePageState extends State<HomePage> {
  late final Database db;
  bool hasSetUpAlready = false;

  Future<bool> setupDatabase() async {
    if (hasSetUpAlready == false) {
      final directory = await getApplicationDocumentsDirectory();
      final path = '${directory.path}/db.sqlite';
      try {
        db = await openDatabase(path);

        // create the table if it doesn't exist

        final create = '''CREATE TABLE IF NOT EXISTS PEOPLE (
          ID INTEGER PRIMARY KEY AUTOINCREMENT,
          FIRST_NAME STRING NOT NULL,
          LAST_NAME STRING NOT NULL
        )''';

        await db.execute(create);
        hasSetUpAlready = true;
        return true;
      } catch (e) {
        print('error = $e');
        hasSetUpAlready = false;
        return false;
      }
    } else {
      return true;
    }
  }

  Future<List<Person>> fetchPersons() async {
    if (!await setupDatabase()) {
      return [];
    }

    try {
      // read the existing data if any
      final readResult = await db.query(
        'PEOPLE',
        distinct: true,
        columns: ['ID', 'FIRST_NAME', 'LAST_NAME'],
        orderBy: 'ID',
      );

      final people = readResult.map((row) => Person.fromData(row)).toList()
        ..sort();
      return people;
    } catch (e) {
      print('error = $e');
      return [];
    }
  }

  Future<bool> addPerson(String firstName, String lastName) async {
    try {
      await db.insert(
        'PEOPLE',
        {
          'FIRST_NAME': firstName,
          'LAST_NAME': lastName,
        },
      );
      return true;
    } catch (e) {
      print('Error inserting $e');
      return false;
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('SQLite in Flutter'),
      ),
      body: FutureBuilder(
        future: fetchPersons(),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.done:
              final people = snapshot.data as List<Person>;
              return Column(
                children: [
                  ComposeWidget(
                    onCompose: (firstName, lastName) async {
                      await addPerson(firstName, lastName);
                      setState(() {});
                    },
                  ),
                  Expanded(
                    child: ListView.builder(
                      itemCount: people.length,
                      itemBuilder: (context, index) {
                        final person = people[index];
                        return ListTile(
                          title: Text(
                            person.fullName,
                            style: TextStyle(fontSize: 24),
                          ),
                          subtitle: Text(
                            'ID: ${person.id}',
                            style: TextStyle(fontSize: 18),
                          ),
                        );
                      },
                    ),
                  ),
                ],
              );
            default:
              return CircularProgressIndicator();
          }
        },
      ),
    );
  }
}

Circular Progress with Percentage in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class SizedCircularProgressIndicator extends StatelessWidget {
  final double progress;
  final double width;
  final double height;
  final TextStyle? textStyle;
  const SizedCircularProgressIndicator({
    Key? key,
    this.textStyle,
    required this.progress,
    required this.width,
    required this.height,
  }) : super(key: key);

  TextStyle get style => textStyle ?? TextStyle(fontSize: 30.0);
  int get _progress => (progress * 100.0).toInt();

  @override
  Widget build(BuildContext context) {
    return Stack(
      alignment: Alignment.center,
      children: [
        Text('$_progress%', style: style),
        SizedBox(
          width: width,
          height: height,
          child: CircularProgressIndicator(
            backgroundColor: Colors.white70,
            value: progress,
            color: Colors.blueAccent,
            strokeWidth: 3.0,
          ),
        ),
      ],
    );
  }
}

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView.builder(
        scrollDirection: Axis.horizontal,
        itemCount: images.length,
        itemBuilder: (context, index) {
          return WithBlurredBackground(imageUrl: images[index]);
        },
      ),
    );
  }
}

class WithBlurredBackground extends StatelessWidget {
  final String imageUrl;

  const WithBlurredBackground({Key? key, required this.imageUrl})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox.expand(
      child: Stack(
        alignment: Alignment.center,
        fit: StackFit.passthrough,
        children: [
          SizedBox.expand(
            child: ClipRect(
              child: ImageFiltered(
                imageFilter: ImageFilter.blur(
                  sigmaX: 10.0,
                  sigmaY: 10.0,
                ),
                child: Image.network(
                  imageUrl,
                  fit: BoxFit.fitHeight,
                ),
              ),
            ),
          ),
          NetworkImageWithProgress(url: imageUrl),
        ],
      ),
    );
  }
}

class NetworkImageWithProgress extends StatelessWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Image.network(
      url,
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return SizedCircularProgressIndicator(
            height: 100,
            width: 100,
            progress: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

Opening URLs in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';

class Person {
  final String profileUrl;
  final String name;
  final String email;
  final String phoneNumber;
  final String websiteUrl;

  const Person({
    Key? key,
    required this.profileUrl,
    required this.name,
    required this.email,
    required this.phoneNumber,
    required this.websiteUrl,
  });

  Person.vandad()
      : profileUrl = 'https://bit.ly/3jwusS0',
        name = 'Vandad Nahavandipoor',
        email = 'vandad.np@gmail.com',
        phoneNumber = '071234567',
        websiteUrl = 'https://pixolity.se';
}

void open(String url) async {
  if (await canLaunch(url)) {
    await launch(url);
  }
}

class PersonNameView extends StatelessWidget {
  final Person person;
  const PersonNameView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      person.name,
      style: TextStyle(
        fontSize: 20,
        fontWeight: FontWeight.bold,
        color: Colors.black,
      ),
    );
  }
}

class PersonEmailView extends StatelessWidget {
  final Person person;
  const PersonEmailView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        open('mailto:${person.email}');
      },
      child: Text(
        'πŸ’Œ Email me',
        style: TextStyle(fontSize: 20.0),
      ),
    );
  }
}

class PersonPhoneView extends StatelessWidget {
  final Person person;
  const PersonPhoneView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        open('tel://${person.phoneNumber}');
      },
      child: Text(
        'πŸ€™πŸ» Call me',
        style: TextStyle(fontSize: 20.0),
      ),
    );
  }
}

class PersonWebsiteView extends StatelessWidget {
  final Person person;
  const PersonWebsiteView(this.person, {Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return TextButton(
      onPressed: () {
        open(person.websiteUrl);
      },
      child: Text(
        '🌍 Visit my website',
        style: TextStyle(fontSize: 20.0),
      ),
    );
  }
}

const bigText = TextStyle(fontSize: 20.0);

class PersonView extends StatelessWidget {
  final Person person;
  const PersonView({Key? key, required this.person}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
          color: Colors.blue[50],
          borderRadius: BorderRadius.circular(16.0),
          border: Border.all(color: Colors.white, width: 3.0),
          boxShadow: [
            BoxShadow(
              blurRadius: 30.0,
              color: Colors.black.withAlpha(50),
              spreadRadius: 20.0,
            ),
          ]),
      child: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            CircleAvatar(
              radius: 100.0,
              backgroundImage: NetworkImage(person.profileUrl),
            ),
            SizedBox(height: 10),
            PersonNameView(person),
            PersonEmailView(person),
            PersonPhoneView(person),
            PersonWebsiteView(person)
          ],
        ),
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: SingleChildScrollView(
          child: PersonView(
            person: Person.vandad(),
          ),
        ),
      ),
    );
  }
}

Commodore 64 Screen in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

const textColor = Color.fromRGBO(156, 156, 247, 1);

class BoxPainter extends CustomPainter {
  final bool isBlinking;
  BoxPainter({required this.isBlinking});

  @override
  void paint(Canvas canvas, Size size) {
    if (isBlinking) {
      final rect = Rect.fromLTWH(
        size.width / 20.0,
        size.height / 2.8,
        size.width / 24.0,
        size.height / 13.0,
      );
      final paint = Paint()..color = textColor;
      canvas.drawRect(rect, paint);
    }
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => true;
}

class ReadyPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final textStyle = TextStyle(
      color: textColor,
      fontSize: size.width / 45.0,
      fontFamily: 'C64',
    );
    final span = TextSpan(
      text: 'READY',
      style: textStyle,
    );
    final painter = TextPainter(
      text: span,
      textDirection: TextDirection.ltr,
    );

    painter.layout(
      minWidth: 0,
      maxWidth: size.width,
    );
    final offset = Offset(
      painter.width / 2.0,
      painter.height * 8.0,
    );
    painter.paint(canvas, offset);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class SubTitlePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final textStyle = TextStyle(
      color: textColor,
      fontSize: size.width / 45.0,
      fontFamily: 'C64',
    );
    final span = TextSpan(
      text: '64K RAM SYSTEM 38911 BASIC BYTES FREE',
      style: textStyle,
    );
    final painter = TextPainter(
      text: span,
      textDirection: TextDirection.ltr,
    );

    painter.layout(
      minWidth: 0,
      maxWidth: size.width,
    );
    final offset = Offset(
      size.width - painter.width - (size.width / 11),
      painter.height * 6.0,
    );
    painter.paint(canvas, offset);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class TitlePainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final textStyle = TextStyle(
      color: textColor,
      fontSize: size.width / 40.0,
      fontFamily: 'C64',
    );
    final span = TextSpan(
      text: '**** COMMODORE 64 BASIC V2 ****',
      style: textStyle,
    );
    final painter = TextPainter(
      text: span,
      textDirection: TextDirection.ltr,
    );

    painter.layout(
      minWidth: 0,
      maxWidth: size.width,
    );
    final offset = Offset(
      size.width - painter.width - (size.width / 9),
      size.height / 6,
    );
    painter.paint(canvas, offset);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class BackgroundPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final border = size.width / 20.0;

    final color = Color.fromRGBO(
      58,
      57,
      213,
      1,
    );

    final paint = Paint()..color = color;

    final rect = Rect.fromLTWH(
      border,
      border,
      size.width - (border * 2.0),
      size.height - (border * 2.0),
    );

    canvas.drawRect(rect, paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class BorderPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()..color = textColor;
    final rect = Rect.fromLTWH(
      0.0,
      0.0,
      size.width,
      size.height,
    );

    canvas.drawRect(rect, paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class Commodore64Painter extends CustomPainter {
  final bool isBlinking;

  late final List<CustomPainter> painters;

  Commodore64Painter({required this.isBlinking}) {
    painters = [
      BorderPainter(),
      BackgroundPainter(),
      TitlePainter(),
      SubTitlePainter(),
      ReadyPainter(),
      BoxPainter(isBlinking: isBlinking)
    ];
  }

  @override
  void paint(Canvas canvas, Size size) {
    painters.forEach(
      (p) => p.paint(
        canvas,
        size,
      ),
    );
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => painters
      .map((p) => p.shouldRepaint(oldDelegate))
      .reduce((p1, p2) => p1 || p2);
}

class Commodore64 extends StatefulWidget {
  const Commodore64({Key? key}) : super(key: key);

  @override
  State<Commodore64> createState() => _Commodore64State();
}

class _Commodore64State extends State<Commodore64> {
  bool _isBlinking = false;

  final timer = Stream.periodic(Duration(seconds: 1), (value) => value);

  void _triggerRedraw() async {
    await for (final _ in timer) {
      setState(() {
        _isBlinking = !_isBlinking;
      });
    }
  }

  @override
  void initState() {
    super.initState();
    _triggerRedraw();
  }

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(builder: (context, constraints) {
      return Container(
        width: constraints.maxWidth,
        height: constraints.maxWidth / (16.0 / 9.0),
        child: CustomPaint(
          painter: Commodore64Painter(isBlinking: _isBlinking),
        ),
      );
    });
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Commodore64(),
      ),
    );
  }
}

Animated Lists in Flutter



import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

class NetworkImage extends StatelessWidget {
  final String url;
  const NetworkImage({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Image.network(
      url,
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return LinearProgressIndicator(
            value: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

class NetworkImageCard extends StatelessWidget {
  final String url;
  const NetworkImageCard({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        clipBehavior: Clip.antiAlias,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(20.0),
        ),
        child: NetworkImage(
          url: url,
        ),
      ),
    );
  }
}

const imageUrls = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

Stream<String> images() => Stream.periodic(
      Duration(seconds: 3),
      (index) => index % imageUrls.length,
    ).map((index) => imageUrls[index]);

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final GlobalKey<AnimatedListState> _key = GlobalKey();

  List<String> imageUrls = [];

  void populateList() async {
    await for (final url in images()) {
      imageUrls.insert(0, url);
      _key.currentState?.insertItem(
        0,
        duration: Duration(milliseconds: 400),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    populateList();
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated Lists in Flutter'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: AnimatedList(
          key: _key,
          initialItemCount: imageUrls.length,
          itemBuilder: (context, index, animation) {
            final imageUrl = imageUrls[index];
            return SizeTransition(
              sizeFactor: animation.drive(
                CurveTween(curve: Curves.elasticInOut),
              ),
              child: Column(
                children: [
                  NetworkImageCard(url: imageUrl),
                  SizedBox(height: 10.0),
                ],
              ),
            );
          },
        ),
      ),
    );
  }
}

CheckboxListTile in Flutter

import 'package:flutter/material.dart';



enum Item { umbrella, coat, boots }

extension Info on Item {
  String get title {
    switch (this) {
      case Item.umbrella:
        return 'Umbrella';
      case Item.boots:
        return 'Boots';
      case Item.coat:
        return 'Jacket';
    }
  }

  String get icon {
    switch (this) {
      case Item.umbrella:
        return 'β˜‚οΈ';
      case Item.boots:
        return 'πŸ₯Ύ';
      case Item.coat:
        return 'πŸ§₯';
    }
  }
}

typedef OnChecked = void Function(bool);

class Tile extends StatelessWidget {
  final Item item;
  final bool isChecked;
  final OnChecked onChecked;
  const Tile({
    Key? key,
    required this.item,
    required this.isChecked,
    required this.onChecked,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ConstrainedBox(
      constraints: BoxConstraints(minHeight: 100.0),
      child: Center(
        child: CheckboxListTile(
          shape: ContinuousRectangleBorder(),
          value: isChecked,
          secondary: Text(
            item.icon,
            style: TextStyle(fontSize: 30.0),
          ),
          title: Text(
            item.title,
            style: TextStyle(fontSize: 40.0),
          ),
          onChanged: (value) {
            onChecked(value ?? false);
          },
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final Set<Item> _enabledItems = {};

  Widget get listView {
    return ListView.builder(
      shrinkWrap: true,
      itemBuilder: (context, index) {
        final item = Item.values[index];
        final isChecked = _enabledItems.contains(item);
        return Tile(
          isChecked: isChecked,
          item: item,
          onChecked: (isChecked) {
            setState(() {
              if (isChecked) {
                _enabledItems.add(item);
              } else {
                _enabledItems.remove(item);
              }
            });
          },
        );
      },
      itemCount: Item.values.length,
    );
  }

  Widget get title {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Text(
        "Remember to pick all items! It's going to be rainy today!",
        textAlign: TextAlign.center,
        style: TextStyle(fontSize: 40),
      ),
    );
  }

  Widget get readyButton {
    final onPressed = () async {
      // program this
      await showDialog(
        context: context,
        builder: (context) {
          return AlertDialog(
            content: Text('You seem to be ready for a rainy day! βœ…'),
            actions: [
              TextButton(
                onPressed: () {
                  Navigator.of(context).pop();
                },
                child: Text('OK'),
              )
            ],
          );
        },
      );
    };

    final isEnabled = _enabledItems.containsAll(Item.values);

    return FractionallySizedBox(
      widthFactor: 0.8,
      child: ElevatedButton(
        onPressed: isEnabled ? onPressed : null,
        child: Text('Ready!'),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Checkbox List Tile in Flutter'),
      ),
      body: SingleChildScrollView(
        child: Column(
          children: [
            title,
            listView,
            SizedBox(height: 50.0),
            readyButton,
          ],
        ),
      ),
    );
  }
}

- Operator on String in Dart



extension Minus on String {
  String operator -(String rhs) => replaceAll(rhs, '');
}

void testIt() {
  assert('foo bar' - 'foo ' == 'bar');
  assert('foo bar foo' - 'foo' == ' bar ');
  assert('bar' - 'foo' == 'bar');
  assert('BAR' - 'bar' == 'BAR');
  assert('foo' - 'FOO' == 'foo');
  assert('foobarbaz' - 'bar' == 'foobaz');
}

Dart Progress for Future<T>



import 'dart:io' show stdout;
import 'dart:async' show Future, Stream;

const loadingSequence = ['Ⓙ', '⣻', '⣽', '⣾', '⣷', '⣯', '⣟', '⑿'];
const escape = '\x1B[38;5;';
const color = '${escape}1m';
const textColor = '${escape}6m';

String progress({required int value, required String text}) {
  final progress = '$color${loadingSequence[value % loadingSequence.length]}';
  final coloredText = '$textColor$text';
  return '$progress\t$coloredText';
}

Future<T> performWithProgress<T>({
  required Future<T> task,
  required String progressText,
}) {
  final stream = Stream<String>.periodic(
    Duration(milliseconds: 100),
    (value) => progress(
      value: value,
      text: progressText,
    ),
  );

  final subscription = stream.listen(
    (event) {
      stdout.write('\r $event');
    },
  );

  task.whenComplete(() {
    stdout.write('\r βœ…\t$progressText');
    stdout.write('\n');
    subscription.cancel();
  });

  return task;
}

final task1 = Future.delayed(Duration(seconds: 1), () => 'Result 1');
final task2 = Future.delayed(Duration(seconds: 2), () => 'Result 2');
final task3 = Future.delayed(Duration(seconds: 3), () => 'Result 3');

void main(List<String> args) async {
  var result = await performWithProgress(
    task: task1,
    progressText: 'Loading task 1',
  );
  print('\tTask 1 result: $result');
  result = await performWithProgress(
    task: task2,
    progressText: 'Loading task 2',
  );
  print('\tTask 2 result: $result');
  result = await performWithProgress(
    task: task3,
    progressText: 'Loading task 3',
  );
  print('\tTask 3 result: $result');
}

Move Widget Shadows with Animation



import 'package:flutter/material.dart';

class ImageTransition extends AnimatedWidget {
  final String imageUrl;

  Animation<double> get shadowXOffset => listenable as Animation<double>;

  const ImageTransition(this.imageUrl, {shadowXOffset})
      : super(listenable: shadowXOffset);

  @override
  Widget build(BuildContext context) {
    return Container(
      clipBehavior: Clip.antiAlias,
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(20.0),
        boxShadow: [
          BoxShadow(
            blurRadius: 10,
            offset: Offset(shadowXOffset.value, 20.0),
            color: Colors.black.withAlpha(100),
            spreadRadius: -10,
          )
        ],
      ),
      child: Image.network(imageUrl),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class CustomCurve extends CurveTween {
  CustomCurve() : super(curve: Curves.easeInOutSine);
  @override
  double transform(double t) {
    return (super.transform(t) - 0.5) * 25.0;
  }
}

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );
    _animation = CustomCurve().animate(_controller);
    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.repeat(reverse: true);
    return Scaffold(
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Center(
          child: ImageTransition(
            'https://bit.ly/3x7J5Qt',
            shadowXOffset: _animation,
          ),
        ),
      ),
    );
  }
}

Gallery with Blurred Backgrounds in Flutter


import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PageView.builder(
        scrollDirection: Axis.horizontal,
        itemCount: images.length,
        itemBuilder: (context, index) {
          return WithBlurredBackground(imageUrl: images[index]);
        },
      ),
    );
  }
}

class WithBlurredBackground extends StatelessWidget {
  final String imageUrl;

  const WithBlurredBackground({Key? key, required this.imageUrl})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox.expand(
      child: Stack(
        alignment: Alignment.center,
        fit: StackFit.passthrough,
        children: [
          SizedBox.expand(
            child: ClipRect(
              child: ImageFiltered(
                imageFilter: ImageFilter.blur(
                  sigmaX: 10.0,
                  sigmaY: 10.0,
                ),
                child: Image.network(
                  imageUrl,
                  fit: BoxFit.fitHeight,
                ),
              ),
            ),
          ),
          Image.network(imageUrl),
        ],
      ),
    );
  }
}

Custom Path Clippers in Flutter



import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: Padding(
          padding: const EdgeInsets.only(
            top: 40.0,
            left: 10.0,
            right: 10.0,
          ),
          child: Column(
            children: images
                .map((url) => ElevatedNetworkImage(url: url))
                .expand(
                  (img) => [
                    img,
                    SizedBox(height: 30.0),
                  ],
                )
                .toList(),
          ),
        ),
      ),
    );
  }
}

class ElevatedNetworkImage extends StatelessWidget {
  final String url;
  const ElevatedNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return PhysicalShape(
      color: Colors.white,
      clipper: Clipper(),
      elevation: 20.0,
      clipBehavior: Clip.none,
      shadowColor: Colors.white.withAlpha(200),
      child: CutEdges(
        child: Image.network(url),
      ),
    );
  }
}

class Clipper extends CustomClipper<Path> {
  static const variance = 0.2;
  static const reverse = 1.0 - variance;

  @override
  Path getClip(Size size) {
    final path = Path();

    path.moveTo(0.0, size.height * Clipper.variance);
    path.lineTo(size.width * Clipper.variance, 0.0);
    path.lineTo(size.width, 0.0);
    path.lineTo(size.width, size.height * Clipper.reverse);
    path.lineTo(size.width * Clipper.reverse, size.height);
    path.lineTo(0.0, size.height);
    path.lineTo(0.0, size.height * Clipper.variance);
    path.close;
    return path;
  }

  @override
  bool shouldReclip(covariant CustomClipper<Path> oldClipper) => false;
}

class CutEdges extends StatelessWidget {
  final Widget child;

  const CutEdges({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ClipPath(
      clipper: Clipper(),
      child: child,
    );
  }
}

Frost Effect on Images in Flutter



import 'package:flutter/material.dart';

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

final loremIpsum =
    'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.';

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Padding(
          padding: const EdgeInsets.fromLTRB(
            8.0,
            0.0,
            8.0,
            0.0,
          ),
          child: SingleChildScrollView(
            child: Column(
              children: images
                  .map(
                    (url) => GlossyNetworkImageWithProgress(
                      url: url,
                      title: 'Image title',
                      description: loremIpsum,
                    ),
                  )
                  .expand(
                    (image) => [
                      image,
                      SizedBox(height: 16.0),
                    ],
                  )
                  .toList(),
            ),
          ),
        ),
      ),
    );
  }
}

class GlossyNetworkImageWithProgress extends StatefulWidget {
  final String url;
  final String title;
  final String description;

  const GlossyNetworkImageWithProgress(
      {Key? key,
      required this.url,
      required this.title,
      required this.description})
      : super(key: key);

  @override
  _GlossyNetworkImageWithProgressState createState() =>
      _GlossyNetworkImageWithProgressState();
}

class _GlossyNetworkImageWithProgressState
    extends State<GlossyNetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final networkImage = Image.network(
      widget.url,
      fit: BoxFit.fitHeight,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );

    return BottomGloss(
      networkImage: networkImage,
      title: widget.title,
      description: widget.description,
    );
  }
}

class BottomGloss extends StatelessWidget {
  final String title;
  final String description;

  const BottomGloss(
      {Key? key,
      required this.networkImage,
      required this.title,
      required this.description})
      : super(key: key);

  final Image networkImage;

  @override
  Widget build(BuildContext context) {
    return ClipRRect(
      borderRadius: BorderRadius.all(Radius.circular(8.0)),
      child: Stack(
        fit: StackFit.passthrough,
        children: [
          networkImage,
          Container(
            height: 300.0,
            alignment: Alignment.bottomCenter,
            child: ClipRect(
              child: FractionallySizedBox(
                heightFactor: 0.5,
                child: BackdropFilter(
                  filter: ImageFilter.blur(
                    sigmaX: 10.0,
                    sigmaY: 10.0,
                  ),
                  child: BottomContents(
                    title: title,
                    description: description,
                  ),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class BottomContents extends StatelessWidget {
  final String title;
  final String description;

  const BottomContents({
    Key? key,
    required this.title,
    required this.description,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.white.withOpacity(0.4),
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: SingleChildScrollView(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              TitleText(text: title),
              SizedBox(height: 8.0),
              SubTitleText(text: description),
            ],
          ),
        ),
      ),
    );
  }
}

class SubTitleText extends StatelessWidget {
  final String text;
  const SubTitleText({Key? key, required this.text}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      text,
      style: TextStyle(
        color: Colors.black,
        fontSize: 20.0,
      ),
    );
  }
}

class TitleText extends StatelessWidget {
  final String text;
  const TitleText({Key? key, required this.text}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      text,
      style: TextStyle(
        color: Colors.white,
        fontSize: 30.0,
      ),
    );
  }
}

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 300.0,
      width: MediaQuery.of(context).size.width,
      child: child is ProgressIndicator ? Center(child: child) : child,
    );
  }
}

Custom Clippers in Flutter

import 'package:flutter/material.dart';
import 'dart:math' show min;

const gridImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: GridView.count(
        padding: const EdgeInsets.fromLTRB(8.0, 48.0, 8.0, 48.0),
        crossAxisCount: 2,
        mainAxisSpacing: 8.0,
        crossAxisSpacing: 8.0,
        children: gridImages
            .map((url) => NetworkImageWithProgress(url: url))
            .toList(),
      ),
    );
  }
}

class CircularClipper extends CustomClipper<Rect> {
  @override
  Rect getClip(Size size) {
    final center = Offset(
      size.width / 2.0,
      size.height / 2.0,
    );
    final minWidthorHeight = min(size.width, size.height);
    return Rect.fromCenter(
      center: center,
      width: minWidthorHeight,
      height: minWidthorHeight,
    );
  }

  @override
  bool shouldReclip(covariant CustomClipper<Rect> oldClipper) => false;
}

class Circular extends StatelessWidget {
  final Widget child;
  const Circular({Key? key, required this.child}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return ClipOval(
      clipper: CircularClipper(),
      child: child,
    );
  }
}

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 220.0,
      width: MediaQuery.of(context).size.width,
      child: child is ProgressIndicator
          ? Center(child: child)
          : Circular(child: child),
    );
  }
}

class NetworkImageWithProgress extends StatefulWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  _NetworkImageWithProgressState createState() =>
      _NetworkImageWithProgressState();
}

class _NetworkImageWithProgressState extends State<NetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      fit: BoxFit.fitHeight,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

Check if Website is Up or Down in Dart



class UpStatus {
  final bool isUp;
  final DateTime timestamp;
  const UpStatus(this.isUp, this.timestamp);
}

class Pling {
  final String url;
  final Duration interval;
  const Pling({
    required this.url,
    required this.interval,
  });
  Stream<UpStatus> checkIfUp() =>
      Stream.periodic(interval, (_) => DateTime.now()).asyncExpand(
        (now) => HttpClient()
            .headUrl(Uri.parse(url))
            .then((req) => req..followRedirects = false)
            .then((req) => req.close())
            .then((resp) => resp.statusCode)
            .then((statusCode) => statusCode == 200)
            .onError((error, stackTrace) => false)
            .then((isUp) => UpStatus(isUp, now))
            .asStream(),
      );
}

const oneSecond = Duration(seconds: 1);
const url = 'https://dart.dev';

extension IsOrIsNot on bool {
  String get isOrIsNot => this ? 'is' : 'is not';
}

void testIt() async {
  final pling = Pling(
    url: url,
    interval: oneSecond,
  );
  await for (final upStatus in pling.checkIfUp()) {
    final timestamp = upStatus.timestamp;
    final isUpStr = upStatus.isUp.isOrIsNot;
    print('$url $isUpStr up at $timestamp');
  }
}

Section Titles on ListView in Flutter

import 'package:flutter/material.dart';

final List<Section> allSections = [
  Section(
    'Spring',
    [
      'https://cnn.it/3xu58Ap',
      'https://bit.ly/3ueqqC1',
    ],
  ),
  Section(
    'Summer',
    [
      'https://bit.ly/3ojNhLc',
      'https://bit.ly/2VcCSow',
    ],
  ),
  Section(
    'Autumn',
    [
      'https://bit.ly/3ib1TJk',
      'https://bit.ly/2XSpjvq',
    ],
  ),
  Section(
    'Winter',
    [
      'https://bit.ly/3iaQNE7',
      'https://bit.ly/3AY8YE4',
    ],
  ),
];

class Section {
  final String title;
  final List<String> urls;
  const Section(this.title, this.urls);
}

extension ToWidgets on Section {
  Iterable<Widget> toNetworkImageCards() {
    return [
      Padding(
        padding: const EdgeInsets.all(8.0),
        child: Text(
          title,
          style: TextStyle(
            fontSize: 40,
          ),
        ),
      ),
      ...urls.expand(
        (url) => [
          NetworkImageCard(url: url),
          SizedBox(height: 10),
        ],
      ),
    ];
  }
}

class NetworkImageCard extends StatelessWidget {
  final String url;
  const NetworkImageCard({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        child: NetworkImageWithProgress(
          url: url,
        ),
      ),
    );
  }
}

class NetworkImageWithProgress extends StatefulWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  _NetworkImageWithProgressState createState() =>
      _NetworkImageWithProgressState();
}

class _NetworkImageWithProgressState extends State<NetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      fit: BoxFit.fitWidth,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 220.0,
      width: MediaQuery.of(context).size.width,
      child: child is ProgressIndicator ? Center(child: child) : child,
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListView.builder(
        itemBuilder: (context, index) {
          final section = allSections[index];
          return Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: section.toNetworkImageCards().toList(),
          );
        },
        itemCount: allSections.length,
      ),
    );
  }
}

Circular Progress in Flutter



import 'package:flutter/material.dart';

class CustomBox extends StatelessWidget {
  final Widget child;

  const CustomBox({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 220.0,
      width: MediaQuery.of(context).size.width,
      child: Center(child: child),
    );
  }
}

class NetworkImageWithProgress extends StatefulWidget {
  final String url;

  const NetworkImageWithProgress({Key? key, required this.url})
      : super(key: key);

  @override
  _NetworkImageWithProgressState createState() =>
      _NetworkImageWithProgressState();
}

class _NetworkImageWithProgressState extends State<NetworkImageWithProgress>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );

    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      fit: BoxFit.fitWidth,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: CustomBox(
            child: child,
          ),
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return CustomBox(
            child: CircularProgressIndicator(
              backgroundColor: Colors.white70,
              value: bytesLoaded / totalBytes,
              color: Colors.blue[900],
              strokeWidth: 5.0,
            ),
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

final images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3ywzOla',
].map((url) => NetworkImageWithProgress(url: url)).expand(
      (element) => [
        element,
        SizedBox(
          height: 10.0,
        )
      ],
    );

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: Column(
          children: images.toList(),
        ),
      ),
    );
  }
}

Displaying Scroll Wheels in Flutter



import 'package:flutter/material.dart';

class FadingNetworkImage extends StatefulWidget {
  final String url;

  const FadingNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  _FadingNetworkImageState createState() => _FadingNetworkImageState();
}

class _FadingNetworkImageState extends State<FadingNetworkImage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller =
        AnimationController(vsync: this, duration: Duration(seconds: 1));

    _animation = Tween(begin: 0.0, end: 1.0).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(
          opacity: _animation,
          child: child,
        );
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return LinearProgressIndicator(
            value: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

final images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3ywzOla',
].map((i) => NetworkImageCard(url: i));

class NetworkImageCard extends StatelessWidget {
  final String url;
  const NetworkImageCard({
    Key? key,
    required this.url,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        clipBehavior: Clip.antiAlias,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(20.0),
          boxShadow: [
            BoxShadow(
              blurRadius: 5,
              offset: Offset(0, 0),
              color: Colors.black.withAlpha(40),
              spreadRadius: 5,
            )
          ],
        ),
        child: FadingNetworkImage(
          url: url,
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListWheelScrollView(
        itemExtent: 164.0,
        squeeze: 0.9,
        perspective: 0.003,
        children: images.toList(),
      ),
    );
  }
}

Post Messages to Slack with Dart



import 'dart:convert' show utf8;
import 'dart:convert' show json;

class SlackMessage {
  final String? inChannel;
  final String? userName;
  final String message;
  final String? iconEmoji;

  const SlackMessage({
    required this.inChannel,
    required this.userName,
    required this.message,
    required this.iconEmoji,
  });

  Future<bool> send(String webhookUrl) async {
    final payload = {
      'text': message,
      if (inChannel != null) 'channel': inChannel!,
      if (userName != null) 'username': userName!,
      if (iconEmoji != null) 'icon_emoji': iconEmoji!
    };

    final request = await HttpClient().postUrl(Uri.parse(webhookUrl));
    final payloadData = utf8.encode(json.encode(payload));
    request.add(payloadData);
    final response = await request.close();
    return response.statusCode == 200;
  }
}

const webhookUrl = 'put your webhook url here';

void testIt() async {
  final message = SlackMessage(
    inChannel: 'dart',
    userName: 'Flutter',
    message: 'Hello from Dart in Terminal',
    iconEmoji: 'blue_heart:',
  );
  if (await message.send(webhookUrl)) {
    print('Successfully sent the message');
  } else {
    print('Could not send the message');
  }
}

Unwrap List<T?>? in Dart



extension Unwrap<T> on List<T?>? {
  List<T> unwrap() => (this ?? []).whereType<T>().toList();
}

void testOptionalListOfOptionals() {
  final List<int?>? optionalListOfOptionals = [1, 2, null, 3, null];
  final unwrapped = optionalListOfOptionals.unwrap(); // List<int>
  print(unwrapped); // prints [1, 2, 3]
}

void testListOfOptionals() {
  final listOfOptionals = [20, 30, null, 40]; // List<int?>
  final unwrapped = listOfOptionals.unwrap(); // List<int>
  print(unwrapped); // prints [20, 30, 40]
}

void testNormalList() {
  final list = [50, 60, 70]; // List<int>
  final unwrapped = list.unwrap(); // List<int>
  print(unwrapped); // prints [50, 60, 70]
}

Avoiding UI Jitters When Switching Widgets in Flutter



const imageUrls = [
  'https://cnn.it/3xu58Ap', // spring
  'https://bit.ly/2VcCSow', // summer
  'https://bit.ly/3A3zStC', // autumn
  'https://bit.ly/2TNY7wi' // winter
];

extension ToNetworkImage<T extends String> on List<T> {
  List<Widget> toNetworkImages() => map((s) => Image.network(s)).toList();
}

class HomePage extends StatefulWidget {
  @override
  State createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var _currentIndex = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Indexed Stack')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            IndexedStack(
              index: _currentIndex,
              children: imageUrls.toNetworkImages(),
            ),
            TextButton(
              onPressed: () {
                setState(
                  () {
                    _currentIndex++;
                    if (_currentIndex >= imageUrls.length) {
                      _currentIndex = 0;
                    }
                  },
                );
              },
              child: Text('Go to next season'),
            )
          ],
        ),
      ),
    );
  }
}

Detect Redirects in Dart



Future<bool> doesRedirect(String url) => HttpClient()
    .headUrl(Uri.parse(url))
    .then((req) => req..followRedirects = false)
    .then((req) => req.close())
    .then((resp) => resp.statusCode)
    .then((statusCode) => [301, 302, 303, 307, 308].contains(statusCode));

void testIt() async {
  final test1 = await doesRedirect('https://cnn.it/3xu58Ap');
  assert(test1 == true);

  final test2 = await doesRedirect('https://dart.dev');
  assert(test2 == false);

  final test3 = await doesRedirect('https://bit.ly/2VcCSow');
  assert(test3 == true);
}

Proportional Constraints in Flutter



class ProportionalWidthNetworkImage extends StatelessWidget {
  final String url;
  final double widthProportion;

  const ProportionalWidthNetworkImage(
      {Key? key, required this.url, required this.widthProportion})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        return Image.network(
          url,
          loadingBuilder: (context, child, loadingProgress) {
            final widget =
                loadingProgress == null ? child : LinearProgressIndicator();
            return Container(
              width: constraints.maxWidth * widthProportion,
              child: widget,
            );
          },
        );
      },
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ProportionalWidthNetworkImage(
          url: 'https://cnn.it/3xu58Ap',
          widthProportion: 0.8,
        ),
      ),
    );
  }
}

Displaying Cupertino Action Sheets in Flutter



import 'package:flutter/cupertino.dart';

enum Season { spring, summer, autumn, winter }

extension Title on Season {
  String get title => describeEnum(this).capitalized;
}

extension Caps on String {
  String get capitalized => this[0].toUpperCase() + substring(1);
}

extension ToWidget on Season {
  Widget toWidget() {
    switch (this) {
      case Season.spring:
        return Image.network('https://cnn.it/3xu58Ap');
      case Season.summer:
        return Image.network('https://bit.ly/2VcCSow');
      case Season.autumn:
        return Image.network('https://bit.ly/3A3zStC');
      case Season.winter:
        return Image.network('https://bit.ly/2TNY7wi');
    }
  }
}

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Future<Season> _chooseSeason(
  BuildContext context,
  Season currentSeason,
) async {
  CupertinoActionSheet actionSheet(BuildContext context) {
    return CupertinoActionSheet(
      title: Text('Choose your favorite season:'),
      actions: Season.values
          .map(
            (season) => CupertinoActionSheetAction(
              onPressed: () {
                Navigator.of(context).pop(season);
              },
              child: Text(season.title),
            ),
          )
          .toList(),
      cancelButton: CupertinoActionSheetAction(
        onPressed: () {
          Navigator.of(context).pop(currentSeason);
        },
        child: Text('Cancel'),
      ),
    );
  }

  return await showCupertinoModalPopup(
    context: context,
    builder: (context) => actionSheet(context),
  );
}

class _HomePageState extends State<HomePage> {
  var _season = Season.spring;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_season.title),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          _season.toWidget(),
          TextButton(
            onPressed: () async {
              _season = await _chooseSeason(
                context,
                _season,
              );
              setState(() {});
            },
            child: Text('Choose a season'),
          ),
        ],
      ),
    );
  }
}

Rotating List<T> in Dart



extension Rotate<T> on List<T> {
  int _rotationTimes(int places) {
    if (isEmpty) {
      return 0;
    }
    if (places == 0) {
      throw ArgumentError('places should be more than 0');
    }
    return places % length;
  }

  List<T> rotatedRight(int places) {
    final times = _rotationTimes(places);
    if (times == 0) {
      return this;
    } else {
      final cutOff = length - times;
      return sublist(cutOff)..addAll(sublist(0, cutOff));
    }
  }

  List<T> rotatedLeft(int places) {
    final times = _rotationTimes(places);
    if (times == 0) {
      return this;
    } else {
      return sublist(times)..addAll(sublist(0, times));
    }
  }
}

extension Equality<T extends Comparable> on List<T> {
  bool isEqualTo(List<T> other) {
    if (other.length != length) {
      return false;
    }
    for (var i = 0; i < length; i++) {
      if (other[i] != this[i]) {
        return false;
      }
    }
    return true;
  }
}

const arr = [1, 2, 3];

void testIt() {
  assert(arr.rotatedRight(1).isEqualTo([3, 1, 2]));
  assert(arr.rotatedRight(2).isEqualTo([2, 3, 1]));
  assert(arr.rotatedRight(3).isEqualTo([1, 2, 3]));
  assert(arr.rotatedRight(4).isEqualTo([3, 1, 2]));
  assert(arr.rotatedLeft(1).isEqualTo([2, 3, 1]));
  assert(arr.rotatedLeft(2).isEqualTo([3, 1, 2]));
  assert(arr.rotatedLeft(3).isEqualTo([1, 2, 3]));
  assert(arr.rotatedLeft(4).isEqualTo([2, 3, 1]));
}

Displaying SnackBars in Flutter



class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Hello world'),
      ),
      body: Center(
        child: TextButton(
          onPressed: () {
            final now = DateFormat('kk:mm:ss').format(DateTime.now());
            ScaffoldMessenger.of(context).removeCurrentSnackBar();
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(
                behavior: SnackBarBehavior.floating,
                elevation: 5.0,
                backgroundColor:
                    Colors.blue[600]!.withOpacity(0.8).withAlpha(200),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(10),
                  side: BorderSide(
                    color: Colors.black.withOpacity(0.4),
                    width: 3.0,
                  ),
                ),
                content: Text('Some text $now'),
              ),
            );
          },
          child: Text('Show toast'),
        ),
      ),
    );
  }
}

Custom Tab Bar Using ToggleButtons in Flutter



class TabBarButton extends StatelessWidget {
  final IconData icon;
  final double size;

  const TabBarButton({Key? key, required this.icon, this.size = 60.0})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Icon(
        icon,
        size: size,
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Toggle Buttons'),
      ),
      body: Column(
        children: [
          CustomTabBar(),
        ],
      ),
    );
  }
}

class CustomTabBar extends StatefulWidget {
  const CustomTabBar({Key? key}) : super(key: key);

  @override
  _CustomTabBarState createState() => _CustomTabBarState();
}

class _CustomTabBarState extends State<CustomTabBar> {
  var _selection = [false, false, false];

  @override
  Widget build(BuildContext context) {
    return Expanded(
      child: Align(
        alignment: FractionalOffset.bottomCenter,
        child: SafeArea(
          child: ToggleButtons(
            isSelected: _selection,
            onPressed: (index) {
              setState(() {
                _selection = List.generate(
                  _selection.length,
                  (i) => index == i ? true : false,
                );
              });
            },
            selectedColor: Colors.white,
            fillColor: Colors.blue,
            borderRadius: BorderRadius.circular(10.0),
            borderWidth: 4.0,
            borderColor: Colors.blue[400],
            selectedBorderColor: Colors.blue,
            highlightColor: Colors.blue.withOpacity(0.2),
            children: [
              TabBarButton(icon: Icons.settings),
              TabBarButton(icon: Icons.add),
              TabBarButton(icon: Icons.settings_remote)
            ],
          ),
        ),
      ),
    );
  }
}

Hashable Mixins in Dart



enum PetType { cat, dog }

mixin Pet {
  String get name;
  int get age;
  PetType get type;
  @override
  String toString() => 'Pet ($type), name = $name, age = $age';
  @override
  int get hashCode => hashValues(name, age, type);
  @override
  bool operator ==(covariant Pet o) => o.hashCode == hashCode;
}

class Cat with Pet {
  @override
  final String name;
  @override
  final int age;
  @override
  final PetType type;
  const Cat({required this.name, required this.age}) : type = PetType.cat;
}

void testIt() {
  final cats = <Cat>{
    Cat(name: 'Kitty 1', age: 2),
    Cat(name: 'Kitty 2', age: 3),
    Cat(name: 'Kitty 1', age: 2),
  };
  cats.forEach(print);
  /* πŸ‘†πŸ» prints the following:
  Pet (PetType.cat), name = Kitty 1, age = 2
  Pet (PetType.cat), name = Kitty 2, age = 3
  */
}

Flutter Tips and Tricks in Terminal



import 'dart:convert' show utf8;
import 'dart:io' show HttpClient, exit, Process, stderr;
import 'dart:math' show Random;

const rawBlobRoot =
    'https://raw.githubusercontent.com/vandadnp/flutter-tips-and-tricks/main/';

void main(List<String> args) async {
  final url = Uri.https('bit.ly', '/2V1GKsC');
  try {
    final client = HttpClient();
    final images = await client
        .getUrl(url)
        .then((req) => req.close())
        .then((resp) => resp.transform(utf8.decoder).join())
        .then((body) => body.split('\n').map((e) => e.trim()))
        .then((iter) => iter.toList())
        .then((list) => list..retainWhere((s) => s.endsWith('.jpg)')))
        .then((imageList) => imageList.map((e) => e.replaceAll('![](', '')))
        .then((imageList) => imageList.map((e) => e.replaceAll(')', '')))
        .then((iter) => iter.toList());

    final found = images[Random().nextInt(images.length)];
    final result = '$rawBlobRoot$found';
    await Process.run('open', [result]);
    exit(0);
  } catch (e) {
    stderr.writeln('Could not proceed due to $e');
    exit(1);
  }
}

Searching List<List<T>> in Dart



const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const arr3 = [7, 8, 9];
const arr = [arr1, arr2, arr3];

extension FlattenFind<T extends Comparable> on Iterable<Iterable<T>> {
  bool containsElement(T value) {
    for (final arr in this) {
      if (arr.contains(value)) {
        return true;
      }
    }
    return false;
  }
}

void testIt() {
  assert(arr.containsElement(2));
  assert(arr.containsElement(8));
  assert(!arr.containsElement(10));
  assert(!arr.containsElement(10));
}

Cloning Objects in Dart



class Person {
  final Map<String, Object> _values;
  static const FIRST_NAME_KEY = 'FIRST_NAME';
  static const LAST_NAME_KEY = 'LAST_NAME';

  Person.from(Map<String, Object> props) : _values = props;

  Person({
    required String firstName,
    required String lastName,
    Map<String, Object>? props,
  }) : _values = {
          FIRST_NAME_KEY: firstName,
          LAST_NAME_KEY: lastName,
        };

  @override
  bool operator ==(covariant Person other) =>
      other.firstName == firstName && other.lastName == lastName;

  @override
  String toString() => _values.toString();
}

extension Properties on Person {
  String get firstName => _values[Person.FIRST_NAME_KEY].toString();
  set firstName(String newValue) => _values[Person.FIRST_NAME_KEY] = newValue;

  String get lastName => _values[Person.LAST_NAME_KEY].toString();
  set lastName(String newValue) => _values[Person.LAST_NAME_KEY] = newValue;
}

extension Clone on Person {
  Person clone([Map<String, Object>? additionalProps]) =>
      Person.from(Map.from(_values)..addAll(additionalProps ?? {}));
}

extension Subscripts on Person {
  Object? operator [](String key) => _values[key];
  operator []=(String key, Object value) => _values[key] = value;
}

void testIt() {
  final foo = Person(
    firstName: 'Foo Firstname',
    lastName: 'Foo Lastname',
  );
  print(foo); // {FIRST_NAME: Foo Firstname, LAST_NAME: Foo Lastname}
  final copyOfFoo = foo.clone();
  print(copyOfFoo); // {FIRST_NAME: Foo Firstname, LAST_NAME: Foo Lastname}
  final bar = foo.clone({'age': 30});
  print(bar); // {FIRST_NAME: Foo Firstname, LAST_NAME: Foo Lastname, age: 30}
  assert(foo == copyOfFoo);
  assert(foo == bar);
  assert(foo['age'] == null);
  assert(copyOfFoo['age'] == null);
  assert(bar['age'] == 30);
}

Color Filters in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var sliderValue = 0.0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Color Filters in Flutter!'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          ColorFiltered(
            colorFilter: ColorFilter.mode(
              Colors.orange.withOpacity(sliderValue),
              BlendMode.colorBurn,
            ),
            child: Image.network('https://tinyurl.com/4vtvh35h'),
          ),
          Slider(
            value: sliderValue,
            onChanged: (value) {
              setState(() {
                sliderValue = value;
              });
            },
          )
        ],
      ),
    );
  }
}

Flattening Lists in Dart



class Person {
  final String name;
  const Person(this.name);
  @override
  String toString() => 'Person: $name';
}

class House {
  final List<Person>? tennants;
  final List<Person> builders;
  const House({
    required this.tennants,
    required this.builders,
  });
}

const houses = [
  House(tennants: null, builders: [
    Person('Builder 1'),
  ]),
  House(tennants: [
    Person('Tennant 1'),
    Person('Tennant 2'),
  ], builders: [
    Person('Builder 3')
  ]),
];

extension OptionalFlattend<T> on Iterable<List<T>?> {
  Iterable<T> flattened() => expand((e) => e ?? []);
}

void testOptionalFlatten() {
  final allTennants = houses.map((h) => h.tennants).flattened();
  print(allTennants); // Person: Tennant 1, Person: Tennant 2
}

extension Flattend<T> on Iterable<List<T>> {
  Iterable<T> flattened() => expand((e) => e);
}

void testNonOptionalFlatten() {
  final allBuilders = houses.map((h) => h.builders).flattened();
  print(allBuilders); // Person: Builder 1, Person: Builder 2
}

void testIt() {
  testOptionalFlatten();
  testNonOptionalFlatten();
}

Managing Duplicates in List<T> in Dart



extension Duplicates<T> on List<T> {
  void addAllByAvoidingDuplicates(Iterable<T> values) =>
      replaceRange(0, length, {
        ...([...this] + [...values])
      });

  int get numberOfDuplicates => length - {...this}.length;

  bool get containsDuplicates => numberOfDuplicates > 0;

  List<T> get uniques => [
        ...{...this}
      ];

  void removeDuplicates() => replaceRange(
        0,
        length,
        uniques,
      );

  List<T> get duplicates => [
        for (var i = 0; i < length; i++)
          [...this].skip(i + 1).contains(this[i]) ? this[i] : null
      ].whereType<T>().toList();
}

void testIt() {
  final values = [3, 2, 10, 30, 40, 30, 100, 10];

  assert(values.numberOfDuplicates == 2);
  assert(values.containsDuplicates == true);

  assert(values.uniques.length == values.length - 2);
  print(values.uniques); // [3, 2, 10, 30, 40, 100]

  values.removeDuplicates();
  print(values); // [3, 2, 10, 30, 40, 100]

  assert(values.numberOfDuplicates == 0);
  assert(!values.containsDuplicates);
  assert(values.duplicates.isEmpty);

  values.addAllByAvoidingDuplicates([3, 2, 10, 200]);
  print(values); // [3, 2, 10, 30, 40, 100, 200]
  assert(values.containsDuplicates == false);
}

FlatMap and CompactMap in Dart



extension CompactMap<T> on List<T> {
  List<E> compactMap<E>(E? Function(T element) f) {
    Iterable<E> imp(E? Function(T element) f) sync* {
      for (final value in this) {
        final mapped = f(value);
        if (mapped != null) {
          yield mapped;
        }
      }
    }

    return imp(f).toList();
  }
}

extension FlatMap<T> on T? {
  E? flatMap<E>(E? Function(T value) f) {
    if (this != null) {
      return f(this!);
    } else {
      return null;
    }
  }
}

void testIt() {
  final foo = [1, 2, null, 3, null, 4];
  final bar = foo.compactMap((element) => element.flatMap((e) => e * 2));
  print(bar); // prints 2, 4, 6, 8
}

Equality of List<T> in Dart



extension Equality<T extends Comparable> on List<T> {
  bool isEqualTo(List<T> other) {
    if (other.length != length) {
      return false;
    }
    for (var i = 0; i < length; i++) {
      if (other[i] != this[i]) {
        return false;
      }
    }
    return true;
  }
}

int ascendingComparator<T extends Comparable>(T lhs, T rhs) =>
    lhs.compareTo(rhs);
int descendingComparator<T extends Comparable>(T lhs, T rhs) =>
    rhs.compareTo(lhs);

extension Sorted<T extends Comparable> on List<T> {
  List<T> sorted({bool descending = false}) => descending
      ? ([...this]..sort(descendingComparator))
      : ([...this]..sort(ascendingComparator));
}

void testIt() {
  assert([1, 2, 3].isEqualTo([1, 2, 3]));
  assert(![1, 2, 3].isEqualTo([1, 2, 2]));
  assert([3, 1, 2].sorted().isEqualTo([1, 2, 3]));
  assert(![3, 1, 2].sorted().isEqualTo([3, 1, 2]));
  assert(['Foo', 'Bar', 'Baz'].isEqualTo(['Foo', 'Bar', 'Baz']));
  assert(!['Foo', 'Bar', 'Baz'].isEqualTo(['foo', 'Bar', 'Baz']));
}

Constants in Dart




class Person {
  final String name;
  final int age;
  const Person({required this.name, required this.age});
}

const foo = Person(name: 'Foo', age: 20);
const foo2 = Person(name: 'Foo', age: 20);
const bar = Person(name: 'Bar', age: 20);

void assert_eq(Object lhs, Object rhs) {
  assert(lhs == rhs);
}

void assert_ne(Object lhs, Object rhs) {
  assert(lhs != rhs);
}

void testIt() {
  assert_eq(foo, foo2);
  assert_ne(foo, bar);
  assert_ne(foo2, bar);
}

Displaying Scrollable Bottom Sheets in Flutter



class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Scrollable Sheet')),
      body: DraggableScrollableSheet(
        initialChildSize: 0.2,
        minChildSize: 0.2,
        maxChildSize: 0.8,
        builder: (context, scrollController) {
          return Container(
            decoration: decoration(),
            clipBehavior: Clip.antiAlias,
            child: SingleChildScrollView(
              controller: scrollController,
              child: column(),
            ),
          );
        },
      ),
    );
  }
}

const urls = [
  'https://tinyurl.com/4vtvh35h',
  'https://tinyurl.com/pujhs55w',
  'https://tinyurl.com/u5k7zueh',
];

List<Widget> imageWithLoremIpsum(String uri) => [
      Image.network(uri),
      SizedBox(height: 10),
      loremIpsum(),
      SizedBox(height: 10),
    ];

Column column() => Column(
      children: imageWithLoremIpsum(urls[0]) +
          imageWithLoremIpsum(urls[1]) +
          imageWithLoremIpsum(urls[2]),
    );

Text loremIpsum() => Text(
      'Lorem ipsum ' * 10,
      textAlign: TextAlign.center,
    );

BoxDecoration decoration() => BoxDecoration(
      border: Border.all(color: Colors.white),
      borderRadius: BorderRadius.only(
        topLeft: Radius.circular(10),
        topRight: Radius.circular(10),
      ),
      color: Colors.white70,
    );

YouTube Ad Remover in Dart



import 'dart:io' show stdout, stderr, exitCode;
import 'package:collection/collection.dart' show IterableExtension;

// example argument: https://www.youtube.com/watch?v=mtETXtSP0pA
void main(List<String> args) async {
  if (args.isEmpty) {
    stdout.writeln('usage: dart youtube.dart "https://..."');
    return;
  }

  final link =
      args.firstWhereOrNull((element) => Uri.tryParse(element) != null);

  if (link == null) {
    stderr.writeln('No YouTube url found');
    exitCode = 1;
    return;
  }

  try {
    final uri = Uri.parse(link);
    if (uri.scheme.toLowerCase() != 'https' ||
        uri.host.toLowerCase() != 'www.youtube.com' ||
        uri.queryParameters['v'] == null) {
      throw FormatException();
    } else {
      final videoId = uri.queryParameters['v'];
      final embedUri = Uri.parse('${uri.scheme}://${uri.host}/embed/$videoId');
      stdout.writeln(embedUri);
      exitCode = 0;
    }
  } on FormatException catch (e) {
    stderr.writeln('Invalid Uri, try again! err = $e');
    exitCode = 1;
    return;
  }
}

Fade Between Widgets in Flutter



const urls = [
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
];

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var isShowingFirstImage = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('AnimatedCrossFade in Flutter'),
      ),
      body: Center(
        child: AnimatedCrossFade(
          layoutBuilder: (topChild, topChildKey, bottomChild, bottomChildKey) {
            return GestureDetector(
              onTap: () {
                setState(() {
                  isShowingFirstImage = !isShowingFirstImage;
                });
              },
              child: AnimatedCrossFade.defaultLayoutBuilder(
                  topChild, topChildKey, bottomChild, bottomChildKey),
            );
          },
          firstChild: Image.network(urls[0]),
          secondChild: Image.network(urls[1]),
          crossFadeState: isShowingFirstImage
              ? CrossFadeState.showFirst
              : CrossFadeState.showSecond,
          duration: Duration(milliseconds: 400),
        ),
      ),
    );
  }
}

Sort Descriptors in Dart



int ascendingComparator<T extends Comparable>(T lhs, T rhs) =>
    lhs.compareTo(rhs);
int descendingComparator<T extends Comparable>(T lhs, T rhs) =>
    rhs.compareTo(lhs);

extension Sorted<T extends Comparable> on List<T> {
  List<T> sorted({bool descending = false}) => descending
      ? (this..sort(descendingComparator))
      : (this..sort(ascendingComparator));
}

class Person implements Comparable {
  final int age;
  final String name;
  const Person({required this.age, required this.name});
  @override
  int compareTo(covariant Person other) => age.compareTo(other.age);
  @override
  String toString() => 'Person, name = $name ($age)';
}

void testIt() {
  final people = [
    Person(age: 39, name: 'Father Foo'),
    Person(age: 40, name: 'Mother Bar'),
    Person(age: 13, name: 'Son Baz'),
  ];

  print('ascending sort');
  people.sorted().forEach(print);
  // prints Son Baz (13), Father Foo (39), Mother Bar (40)
  print('descending sort');
  people.sorted(descending: true).forEach(print);
  // prints Mother Bar (40), Father Foo (39), Son Baz (13)
}

User Sortable Columns and Tables in Flutter



class Language {
  final String name;
  final Image image;
  const Language(this.name, this.image);
  Language.dart()
      : name = 'Dart',
        image = Image.network('https://bit.ly/3yH1Ivj');
  Language.rust()
      : name = 'Rust',
        image = Image.network('https://bit.ly/3lPTqhb');
  Language.python()
      : name = 'Python',
        image = Image.network('https://bit.ly/3iCFCEP');

  Language.java()
      : name = 'Java',
        image = Image.network('https://bit.ly/3CCapJH');
  static List<Language> all = [
    Language.dart(),
    Language.rust(),
    Language.python(),
    Language.java(),
  ];
}

extension Sort on List<Language> {
  void sortByName(bool ascending) => sort((lhs, rhs) =>
      ascending ? lhs.name.compareTo(rhs.name) : rhs.name.compareTo(lhs.name));
}

List<DataRow> rows(List<Language> langs) => langs
    .map(
      (l) => DataRow(
        cells: [
          DataCell(
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: l.image,
            ),
          ),
          DataCell(Text(l.name)),
        ],
      ),
    )
    .toList();

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final List<Language> _langs = Language.all..sortByName(true);
  int sortedColumnIndex = 1;
  var isSortedAscending = true;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('WhatsApp')),
      body: DataTable(
        sortAscending: isSortedAscending,
        sortColumnIndex: sortedColumnIndex,
        columns: [
          DataColumn(label: Text('Image')),
          DataColumn(
            label: Text('Name'),
            onSort: (columnIndex, ascending) {
              setState(() {
                sortedColumnIndex = columnIndex;
                isSortedAscending = ascending;
                _langs.sortByName(ascending);
              });
            },
          ),
        ],
        rows: rows(_langs),
      ),
    );
  }
}

Content-Length of List<Uri> in Dart

Recursive Dot Notation on Maps in Dart




final person = {
  'firstName': 'Foo',
  'lastName': 'Bar',
  'age': 30,
  'address': {
    'street': {
      'name': 'Baz street',
      'numberOfHouses': 20,
    },
    'houseNumber': '#20',
    'city': 'Stockholm',
    'country': 'Sweden'
  },
};

extension KeyPath on Map {
  Object? valueFor({required String keyPath}) {
    final keysSplit = keyPath.split('.');
    final thisKey = keysSplit.removeAt(0);
    final thisValue = this[thisKey];
    if (keysSplit.isEmpty) {
      return thisValue;
    } else if (thisValue is Map) {
      return thisValue.valueFor(keyPath: keysSplit.join('.'));
    }
  }
}

void testIt() {
  assert(person.valueFor(keyPath: 'firstName') == 'Foo');
  assert(person.valueFor(keyPath: 'age') == 30);
  assert(person.valueFor(keyPath: 'address.street.name') == 'Baz street');
  assert(person.valueFor(keyPath: 'address.houseNumber') == '#20');
}

Allow User Selection of Text in Flutter



const text = 'Flutter is an open-source UI software development'
    ' kit created by Google. It is used to develop cross platform applications'
    ' for Android, iOS, Linux, Mac, Windows, Google Fuchsia, '
    'and the web from a single codebase.';

const imageUrl = 'https://bit.ly/3gT5Qk2';

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Selectable Text in Flutter'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Image.network(imageUrl),
          SizedBox(height: 10.0),
          Padding(
            padding: const EdgeInsets.all(8.0),
            child: SelectableText(
              text,
              textAlign: TextAlign.center,
              showCursor: true,
              cursorColor: Colors.blue,
              toolbarOptions: ToolbarOptions(
                copy: true,
                selectAll: true,
              ),
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.w300,
              ),
            ),
          ),
        ],
      ),
    );
  }
}

Placing Constraints on Widgets in Flutter



const dashes = [
  'https://bit.ly/3gHlTCU',
  'https://bit.ly/3wOLO1c',
  'https://bit.ly/3cXWD9j',
  'https://bit.ly/3gT5Qk2',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('ConstrainedBox in Flutter'),
      ),
      body: InteractiveViewer(
        minScale: 1.0,
        maxScale: 2.0,
        child: SingleChildScrollView(
          scrollDirection: Axis.vertical,
          child: Table(
            defaultVerticalAlignment: TableCellVerticalAlignment.middle,
            children: dashes
                .map(
                  (dash) => TableRow(
                    children: [
                      ConstrainedBox(
                        constraints: BoxConstraints(
                          minHeight: 300,
                        ),
                        child: Image.network(dash),
                      ),
                    ],
                  ),
                )
                .toList(),
          ),
        ),
      ),
    );
  }
}

Animating Position Changes in Flutter



class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var isMovedUp = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('AnimatedPositioned in Flutter')),
      body: Center(
        child: GestureDetector(
          onTap: () => setState(() => isMovedUp = !isMovedUp),
          child: Stack(
            clipBehavior: Clip.none,
            alignment: Alignment.center,
            children: [
              Image.network('https://bit.ly/2VcCSow'),
              Text(
                'Summer 😎',
                style: TextStyle(
                  fontSize: 30,
                  color: Colors.black,
                ),
              ),
              AnimatedPositioned(
                duration: Duration(seconds: 1),
                bottom: isMovedUp ? 140 : 10.0,
                curve: Curves.elasticInOut,
                child: CircleAvatar(
                  radius: 100,
                  backgroundImage: NetworkImage('https://bit.ly/3cXWD9j'),
                  backgroundColor: Colors.orange[300],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Transitioning Between Widgets in Flutter



enum Season { spring, summer, autumn, winter }

extension Caps on String {
  String get capitalized => this[0].toUpperCase() + substring(1);
}

extension Title on Season {
  String get title => describeEnum(this).capitalized;
}

class TitledImage {
  final String title;
  final Uri uri;
  final ValueKey key;
  const TitledImage(this.title, this.uri, this.key);

  TitledImage.spring()
      : title = Season.spring.title,
        uri = Uri.https('cnn.it', '/3xu58Ap'),
        key = ValueKey(1);

  TitledImage.summer()
      : title = Season.summer.title,
        uri = Uri.https('bit.ly', '/2VcCSow'),
        key = ValueKey(2);

  TitledImage.autumn()
      : title = Season.autumn.title,
        uri = Uri.https('bit.ly', '/3A3zStC'),
        key = ValueKey(3);

  TitledImage.winter()
      : title = Season.winter.title,
        uri = Uri.https('bit.ly', '/2TNY7wi'),
        key = ValueKey(4);
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var _img = TitledImage.summer();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(_img.title)),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          AnimatedSwitcher(
            switchInCurve: Curves.easeIn,
            switchOutCurve: Curves.easeOut,
            duration: Duration(milliseconds: 300),
            transitionBuilder: (child, animation) {
              return FadeTransition(opacity: animation, child: child);
            },
            child: Image.network(
              _img.uri.toString(),
              key: _img.key,
            ),
          ),
          getButtons(),
        ],
      ),
    );
  }

  Widget getButtons() {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.spring()),
          child: Text(Season.spring.title),
        ),
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.summer()),
          child: Text(Season.summer.title),
        ),
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.autumn()),
          child: Text(Season.autumn.title),
        ),
        TextButton(
          onPressed: () => setState(() => _img = TitledImage.winter()),
          child: Text(Season.winter.title),
        ),
      ],
    );
  }
}

Doubly Linked Lists in Dart



class Person extends LinkedListEntry<Person> {
  final String name;
  final int age;
  Person({
    required this.name,
    required this.age,
  });

  @override
  String toString() => 'Person name = $name, age = $age';
}

void testIt() {
  final persons = LinkedList<Person>();
  final dad = Person(name: 'Father Foo', age: 47);
  final mom = Person(name: 'Mother Bar', age: 47);
  final daughter = Person(name: 'Daughter Baz', age: 22);
  persons.addAll([dad, mom, daughter]);

  print(persons.first.previous); // null
  print(persons.first); // Person name = Father Foo, age = 47
  print(persons.first.next); // Person name = Mother Bar, age = 47
  print(persons.last.previous); // Person name = Mother Bar, age = 47
  print(persons.first.next?.next); // Person name = Daughter Baz, age = 22
  print(persons.last.next); // null
}

Reordering Items Inside List Views in Flutter



class Item {
  final Color color;
  final String text;
  final UniqueKey uniqueKey;
  Item(this.color, this.text) : uniqueKey = UniqueKey();
}

extension ToListItem on Item {
  Widget toListItem() => LimitedBox(
        key: uniqueKey,
        maxHeight: 200,
        child: Container(
          color: color,
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Text(
              text,
              style: TextStyle(
                color: Colors.white,
                fontSize: 100,
              ),
            ),
          ),
        ),
      );
}

class _HomePageState extends State<HomePage> {
  var items = [
    Item(Colors.deepPurple, 'Foo'),
    Item(Colors.blueGrey, 'Bar'),
    Item(Colors.lightGreen, 'Baz')
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Reordered List View in Flutter'),
      ),
      body: ReorderableListView(
        onReorder: (oldIndex, newIndex) {
          setState(() {
            final item = items.removeAt(oldIndex);
            items.insert(newIndex, item);
          });
        },
        children: items.map((i) => i.toListItem()).toList(),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Custom Stream Transformers in Dart



in this example we have created our own string transformer that
can trim a Stream<String> by trimming whitespace from both
beginning and end of the string
*/

import 'dart:convert' show utf8;

class StringTrimmer extends StreamTransformerBase<String, String> {
  const StringTrimmer();
  @override
  Stream<String> bind(Stream<String> stream) =>
      Stream.fromFuture(stream.join(' ')).map((str) => str.trim());
}

final string =
    '''   A long line of text with spaces in the beginning and the end, 
    divided into three lines just for the purpose of this demonstration    ''';

void testIt() async {
  final bytes = utf8.encode(string);
  final result = await Stream.value(bytes)
      .transform(utf8.decoder)
      .transform(LineSplitter())
      .transform(StringTrimmer())
      .join();
  print(result);
}

Expanding Stream Elements in Dart

/*


in this example we expand every element inside our Stream<int> to
a stream that in turn contains n+1 elements where n is the index generated
by our main stream, that's to say, 0, 1, 2, 3, 4, etc

*/
Stream<int> nestedEvents(int count) {
  return Stream.periodic(
    Duration(seconds: 1),
    (e) => e,
  ).take(count).asyncExpand(
        (i) => Stream.fromIterable(
          Iterable.generate(i + 1),
        ),
      );
}

void testIt() async {
  /* 
  prints the followings in this order
  0, 1
  0, 1, 2
  0, 1, 2, 3
  0, 1, 2, 3, 4
  */
  await for (final value in nestedEvents(5)) {
    print('Value is $value');
  }
}

Consume Streams for a Duration in Dart

extension TakeFor<T> on Stream<T> {
  Stream<T> takeFor(Duration duration) {
    final upTo = DateTime.now().add(duration);
    return takeWhile((_) {
      final now = DateTime.now();
      return now.isBefore(upTo) | now.isAtSameMomentAs(upTo);
    });
  }
}

Stream<DateTime> source() => Stream.periodic(
      Duration(milliseconds: 500),
      (_) => DateTime.now(),
    );

void testIt() async {
  await for (final dateTime in source().takeFor(
    Duration(seconds: 4),
  )) {
    print('date time is $dateTime');
  }
}

Shortening URLs in Dart

import 'dart:convert' show json;

Future<Uri> shortenUri(Uri uri, String bitlyToken) async {
  final client = HttpClient();

  final endpoint = Uri.https('api-ssl.bitly.com', '/v4/shorten');

  final response = await client.postUrl(endpoint).then(
    (req) {

      req.headers
        ..set(HttpHeaders.contentTypeHeader, 'application/json')
        ..set(HttpHeaders.authorizationHeader, 'Bearer $bitlyToken');

      final body = {
        'long_url': uri.toString(),
        'domain': 'bit.ly',
      };
      final bodyBytes = utf8.encode(json.encode(body));
      req.add(bodyBytes);

      return req.close();
    },
  );

  final responseBody = await response.transform(utf8.decoder).join();
  final responseJson = json.decode(responseBody) as Map<String, dynamic>;
  return Uri.parse(responseJson['link']);
}

void testIt() async {
  print(await shortenUri(
    Uri.parse('https://pixolity.se'),
    'XXX',
  ));
}

LimitedBox Widget as ListView Items in Flutter

const images = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

extension ToListItemImage on String {
  Widget toListItemImage() {
    return LimitedBox(
      maxHeight: 150.0,
      child: Image.network(
        this,
        fit: BoxFit.fitWidth,
      ),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Limited Box in Flutter')),
      body: ListView(
        children: images.map((str) => str.toListItemImage()).toList(),
      ),
    );
  }
}

Generically Convert Anything to Int in Dart

extension ToInt on Object {
  int toInt() {
    final list = [
      if (this is Iterable<Object>)
        ...(List.of(this as Iterable<Object>))
      else if (this is int)
        [this as int]
      else
        (double.tryParse(toString()) ?? 0.0).round()
    ];
    return list
        .map((e) => (double.tryParse(e.toString()) ?? 0.0).round())
        .reduce((lhs, rhs) => lhs + rhs);
  }
}

void testIt() {
  assert(1.toInt() == 1);
  assert((2.2).toInt() == 2);
  assert((2.0).toInt() == 2);
  assert('3'.toInt() == 3);
  assert(['4', '5'].toInt() == 9);
  assert([4, 5].toInt() == 9);
  assert(['2.4', '3.5'].toInt() == 6);
  assert(['2', '3.5'].toInt() == 6);
  assert({'2', 3, '4.2'}.toInt() == 9);
  assert(['2', 3, '4.2', 5.3].toInt() == 14);
}

Validating URL Certificates in Dart

import 'dart:io' show HttpClient;

Future<bool> isSecuredWithValidCert(String uriString) async {
  final uri = Uri.parse(uriString);
  final client = HttpClient();
  try {
    await client.headUrl(uri).then((r) => r.close());
    return true;
  } on HandshakeException {
    return false;
  }
}

void testIt() async {
  await isSecuredWithValidCert('https://expired.badssl.com');
  await isSecuredWithValidCert('https://wrong.host.badssl.com');
  await isSecuredWithValidCert('https://self-signed.badssl.com');
  await isSecuredWithValidCert('https://untrusted-root.badssl.com');
  await isSecuredWithValidCert('https://revoked.badssl.com');
}

Displaying Popup Menus in Flutter

enum ImageAction { copy }

PopupMenuItem<ImageAction> copyButton({VoidCallback? onPressed}) =>
    PopupMenuItem<ImageAction>(
      value: ImageAction.copy,
      child: TextButton.icon(
        icon: Icon(Icons.copy),
        label: Text('Copy'),
        onPressed: onPressed,
      ),
    );

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter'),
      ),
      body: Center(
        child: PopupMenuButton<ImageAction>(
          elevation: 10,
          offset: Offset(0, 50),
          itemBuilder: (_) => [
            copyButton(
              onPressed: () {
                print('Copy the image...');
              },
            ),
          ],
          child: Image.network('https://bit.ly/3ywI8l6'),
        ),
      ),
    );
  }
}

Implementing Drag and Drop in Flutter

class HomePage extends StatefulWidget {
  HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  String? _imageUrl;

  bool shouldAccept(String? value) => Uri.tryParse(value ?? '') != null;

  Widget dragTargetBuilder(
    BuildContext context,
    List<String?> incoming,
    dynamic rejected,
  ) {
    final emptyContainer = Container(
      color: Colors.grey[200],
      height: 200,
      child: Center(
        child: Text('Drag an image here'),
      ),
    );

    if (incoming.isNotEmpty) {
      _imageUrl = incoming.first;
    }

    if (_imageUrl == null) {
      return emptyContainer;
    }

    try {
      final uri = Uri.parse(_imageUrl ?? '');
      return Container(
        color: Colors.grey[200],
        height: 200,
        child: Center(
          child: Image.network(uri.toString()),
        ),
      );
    } on FormatException {
      return emptyContainer;
    }
  }

  static final firstImageUrl = 'https://bit.ly/3xnoJTm';
  static final secondImageUrl = 'https://bit.ly/3hIuC78';
  final firstImage = Image.network(firstImageUrl);
  final secondImage = Image.network(secondImageUrl);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Tooltips in Flutter')),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          children: [
            DragTarget<String>(
              onWillAccept: shouldAccept,
              builder: dragTargetBuilder,
            ),
            SizedBox(height: 10.0),
            DraggableImage(
              imageWidget: firstImage,
              imageUrl: firstImageUrl,
            ),
            SizedBox(height: 10.0),
            DraggableImage(
              imageWidget: secondImage,
              imageUrl: secondImageUrl,
            ),
          ],
        ),
      ),
    );
  }
}

class DraggableImage extends StatelessWidget {
  const DraggableImage({
    Key? key,
    required this.imageWidget,
    required this.imageUrl,
  }) : super(key: key);

  final Image imageWidget;
  final String imageUrl;

  @override
  Widget build(BuildContext context) {
    return Draggable<String>(
      data: imageUrl,
      feedback: Container(
        width: MediaQuery.of(context).size.width,
        decoration: BoxDecoration(
          boxShadow: [
            BoxShadow(
              blurRadius: 30,
              color: Colors.black,
              spreadRadius: 10,
            ),
          ],
        ),
        child: imageWidget,
      ),
      child: imageWidget,
    );
  }
}

Dismissing List Items in Flutter

const gridImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3dLJNeD',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomScrollView(
        slivers: [
          CustomAppBar(),
          CustomGridView(),
          CustomListView(
            imageUrls: gridImages,
          ),
        ],
      ),
    );
  }
}

class _CustomListViewState extends State<CustomListView> {
  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverList(
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            final url = widget.imageUrls[index];
            return Dismissible(
              key: ValueKey(url),
              onDismissed: (_) {
                widget.imageUrls.remove(url);
              },
              background: Container(
                color: Colors.red,
                child: FittedBox(
                  alignment: Alignment.centerRight,
                  fit: BoxFit.fitHeight,
                  child: Icon(Icons.delete, color: Colors.white),
                ),
              ),
              child: Padding(
                padding: const EdgeInsets.only(bottom: 8.0),
                child: Image.network(url),
              ),
            );
          },
          childCount: widget.imageUrls.length,
        ),
      ),
    );
  }
}

class CustomListView extends StatefulWidget {
  final List<String> imageUrls;

  const CustomListView({
    Key? key,
    required this.imageUrls,
  }) : super(key: key);

  @override
  _CustomListViewState createState() => _CustomListViewState();
}

class CustomGridView extends StatelessWidget {
  const CustomGridView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverGrid(
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 3,
          mainAxisSpacing: 10,
          crossAxisSpacing: 10,
          childAspectRatio: 1.0,
        ),
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            return Container(
              width: 100,
              height: 100,
              child: Image.network(gridImages[index]),
            );
          },
          childCount: gridImages.length,
        ),
      ),
    );
  }
}

class CustomAppBar extends StatelessWidget {
  const CustomAppBar({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverAppBar(
      backgroundColor: Colors.orange[300],
      forceElevated: true,
      pinned: false,
      snap: false,
      floating: true,
      expandedHeight: 172,
      flexibleSpace: FlexibleSpaceBar(
        title: Text(
          'Flutter',
          style: TextStyle(
            fontSize: 30,
            color: Colors.white,
            decoration: TextDecoration.underline,
          ),
        ),
        collapseMode: CollapseMode.parallax,
        background: Image.network('https://bit.ly/3x7J5Qt'),
      ),
    );
  }
}

Animating Widgets with Ease in Flutter

class Ball extends StatefulWidget {
  const Ball({Key? key}) : super(key: key);

  @override
  _BallState createState() => _BallState();
}

class _BallState extends State<Ball> with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 4),
      reverseDuration: Duration(seconds: 4),
    );
    _animation = Tween(begin: 0.0, end: 2 * pi).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.repeat();
    return AnimatedBuilder(
      animation: _animation,
      builder: (context, image) {
        return Transform.rotate(
          angle: _animation.value,
          child: image,
        );
      },
      child: Image.network('https://bit.ly/3xspdrp'),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated Builder in Flutter'),
      ),
      body: Center(
        child: Ball(),
      ),
    );
  }
}

Displaying Tool Tips in Flutter

const imagesAndInfo = [
  ['https://bit.ly/3xnoJTm', 'Stockholm, Sweden'],
  ['https://bit.ly/3hIuC78', 'Dalarna, Sweden'],
  ['https://bit.ly/3wi9mdG', 'Brighton, UK'],
  ['https://bit.ly/3dSSMuy', 'Hove, UK'],
  ['https://bit.ly/3xoWCmV', 'Kerala, India'],
  ['https://bit.ly/3hGmjZC', 'Salvador da Bahia, Brazil']
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Tooltips in Flutter')),
      body: ListView.builder(
        itemCount: imagesAndInfo.length,
        itemBuilder: (_, index) {
          return Padding(
            padding: const EdgeInsets.only(top: 8.0, left: 8.0, right: 8.0),
            child: Tooltip(
              decoration: BoxDecoration(
                color: Colors.black,
                boxShadow: [
                  BoxShadow(
                    color: Colors.white.withAlpha(180),
                    offset: Offset.zero,
                    spreadRadius: 30.0,
                    blurRadius: 30.0,
                  ),
                ],
                borderRadius: BorderRadius.all(Radius.circular(8.0)),
              ),
              textStyle: TextStyle(fontSize: 20, color: Colors.white),
              message: imagesAndInfo[index][1],
              child: Image.network(
                imagesAndInfo[index][0],
              ),
            ),
          );
        },
      ),
    );
  }
}

Displaying Assorted Widgets Inside TableView in Flutter

const natureUrls = [
  'https://bit.ly/3dAtFwy',
  'https://bit.ly/36cHehe',
  'https://bit.ly/365uqt1',
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3jBvJYU',
  'https://bit.ly/3yhbHHi'
];

extension ToImage on String {
  Widget toPaddedNetworkImage() => Padding(
        padding: const EdgeInsets.all(8.0),
        child: Image.network(this),
      );
}

extension ToImages on List<String> {
  List<Widget> toPaddedNetworkImages() =>
      map((str) => str.toPaddedNetworkImage()).toList();
}

extension ToTableRow on List<Widget> {
  TableRow toTableRow() => TableRow(children: this);
}

class ListPaginator<T> extends Iterable {
  final List<List<T>> list;
  ListPaginator({required List<T> input, required int itemsPerPage})
      : list = [
          for (var i = 0; i < input.length; i += itemsPerPage)
            input.getRange(i, min(input.length, i + itemsPerPage)).toList(),
        ];

  @override
  Iterator get iterator => list.iterator;
}

class HomePage extends StatelessWidget {
  final provider = ListPaginator<String>(
    input: natureUrls,
    itemsPerPage: 3,
  );
  HomePage({Key? key}) : super(key: key);

  Iterable<TableRow> getRows() sync* {
    for (final List<String> urlBatch in provider) {
      final networkImages = urlBatch.toPaddedNetworkImages();
      yield TableRow(children: networkImages);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('TableView in Flutter'),
      ),
      body: SingleChildScrollView(
        child: Table(
          defaultVerticalAlignment: TableCellVerticalAlignment.bottom,
          children: getRows().toList(),
        ),
      ),
    );
  }
}

Page Indicator with Page View in Flutter

const dashes = [
  'https://bit.ly/3gHlTCU',
  'https://bit.ly/3wOLO1c',
  'https://bit.ly/3cXWD9j',
  'https://bit.ly/3gT5Qk2',
];

class PageText extends StatelessWidget {
  final int current;
  final int total;

  const PageText({
    Key? key,
    required this.current,
    required this.total,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Text(
      'Page ${current + 1} of $total',
      style: TextStyle(fontSize: 30.0, shadows: [
        Shadow(
          offset: Offset(0.0, 1.0),
          blurRadius: 20.0,
          color: Colors.black.withAlpha(140),
        )
      ]),
    );
  }
}

class _HomePageState extends State<HomePage> {
  var _index = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Page Indicator')),
      body: SafeArea(
        child: Column(
          children: [
            Expanded(
              child: PageView.builder(
                onPageChanged: (pageIndex) {
                  setState(() => _index = pageIndex);
                },
                scrollDirection: Axis.horizontal,
                itemCount: dashes.length,
                itemBuilder: (context, index) {
                  return Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Image.network(dashes[index]),
                      Text('Dash #${index + 1}'),
                    ],
                  );
                },
              ),
            ),
            PageText(current: _index, total: dashes.length)
          ],
        ),
      ),
    );
  }
}

Animating and Moving a Floating Action Button in Flutter

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

const List<FloatingActionButtonLocation> locations = [
  FloatingActionButtonLocation.centerDocked,
  FloatingActionButtonLocation.startDocked,
  FloatingActionButtonLocation.startFloat,
  FloatingActionButtonLocation.centerFloat,
  FloatingActionButtonLocation.endFloat,
  FloatingActionButtonLocation.endDocked
];

extension GoAround<T> on List<T> {
  T elementByGoingAround(int index) {
    final finalIndex = index >= length ? index.remainder(length) : index;
    return this[finalIndex];
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  var _locationIndex = 0;

  FloatingActionButtonLocation get location =>
      locations.elementByGoingAround(_locationIndex);

  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(
        title: Text('Floating Action Button'),
      ),
      floatingActionButtonLocation: location,
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          setState(() => _locationIndex += 1);
        },
        child: Icon(Icons.add),
      ),
      bottomNavigationBar: BottomNavigationBar(
        backgroundColor: Colors.yellow[600],
        selectedItemColor: Colors.black,
        items: [
          BottomNavigationBarItem(
            icon: Icon(Icons.bedtime),
            label: 'Item 1',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.access_alarms),
            label: 'Item 2',
          )
        ],
        currentIndex: 0,
      ),
    );
  }
}

Fading Network Image Widget in Flutter

class FadingNetworkImage extends StatefulWidget {
  final String url;

  const FadingNetworkImage({Key? key, required this.url}) : super(key: key);

  @override
  _FadingNetworkImageState createState() => _FadingNetworkImageState();
}

class _FadingNetworkImageState extends State<FadingNetworkImage>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _animation;

  @override
  void initState() {
    super.initState();

    _controller =
        AnimationController(vsync: this, duration: Duration(seconds: 1));

    _animation = Tween(begin: 0.0, end: 1.0).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Image.network(
      widget.url,
      frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
        _controller.reset();
        _controller.forward();
        return FadeTransition(opacity: _animation, child: child);
      },
      loadingBuilder: (context, child, loadingProgress) {
        final totalBytes = loadingProgress?.expectedTotalBytes;
        final bytesLoaded = loadingProgress?.cumulativeBytesLoaded;
        if (totalBytes != null && bytesLoaded != null) {
          return LinearProgressIndicator(
            value: bytesLoaded / totalBytes,
          );
        } else {
          return child;
        }
      },
      errorBuilder: (context, error, stackTrace) {
        return Text('Error!');
      },
    );
  }
}

const dashes = [
  'https://bit.ly/3gHlTCU',
  'https://bit.ly/3wOLO1c',
  'https://bit.ly/3cXWD9j',
  'https://bit.ly/3gT5Qk2',
];

extension GoAround<T> on List<T> {
  T elementByGoingAround(int index) {
    final finalIndex = index >= length ? index.remainder(length) : index;
    return this[finalIndex];
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  int _index = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Faded Image'),
      ),
      body: Center(
          child: Column(
        children: [
          FadingNetworkImage(
            url: dashes.elementByGoingAround(_index),
          ),
          TextButton(
            onPressed: () {
              setState(() => _index += 1);
            },
            child: Text('Load next Dash'),
          ),
        ],
      )),
    );
  }
}

Transparent Alert Dialogs in Flutter

TextStyle get whiteTextStyle => TextStyle(color: Colors.white);

Future<void> showTextDialog({
  required BuildContext context,
  required String text,
}) {
  return showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.all(
            Radius.circular(10),
          ),
          side: BorderSide(
            color: Colors.white,
            style: BorderStyle.solid,
            width: 2,
          ),
        ),
        backgroundColor: Colors.black.withAlpha(150),
        titleTextStyle: whiteTextStyle,
        contentTextStyle: whiteTextStyle,
        content: Text(text),
        actions: [
          TextButton(
            style: TextButton.styleFrom(primary: Colors.white),
            onPressed: () {
              Navigator.of(context).pop();
            },
            child: Text('OK'),
          )
        ],
      );
    },
  );
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'Rounded Corder Dialog',
        ),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Image.network('https://bit.ly/3ywI8l6'),
          TextButton(
            onPressed: () async {
              await showTextDialog(
                context: context,
                text: 'Hello world',
              );
            },
            child: Text('Show dialog'),
          ),
        ],
      ),
    );
  }
}

Network Image Size in Dart

import 'dart:ui' as ui;

Future<Size> getImageSize(String uri) {
  final image = Image.network('https://bit.ly/3dAtFwy');
  final comp = Completer<ui.Image>();
  image.image
      .resolve(
        ImageConfiguration.empty,
      )
      .addListener(
        ImageStreamListener(
          (ImageInfo info, _) => comp.complete(info.image),
        ),
      );
  return comp.future.then(
    (image) => Size(
      image.width.toDouble(),
      image.height.toDouble(),
    ),
  );
}

void testIt() async {
  final imageSize = await getImageSize('https://bit.ly/3dAtFwy');
  print(imageSize);
  assert(imageSize.width == 2048.0);
  assert(imageSize.height == 1365.0);
  print(imageSize.aspectRatio);
}

Animated Icons in Flutter

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  late final Animation<double> _animation;
  late final AnimationController _controller;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: Duration(seconds: 1),
    );
    _animation = Tween(
      begin: 0.0,
      end: 1.0,
    ).animate(_controller);
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    _controller.repeat(reverse: true);
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated Icons in Fluter'),
      ),
      body: Center(
        child: AnimatedIcon(
          color: Colors.green[300],
          size: MediaQuery.of(context).size.width,
          icon: AnimatedIcons.search_ellipsis,
          progress: _animation,
        ),
      ),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

Custom Scroll Views in Flutter

const gridImages = [
  'https://bit.ly/3x7J5Qt',
  'https://bit.ly/3dLJNeD',
  'https://bit.ly/3ywI8l6',
  'https://bit.ly/3jRSRCu',
  'https://bit.ly/36fNNj9',
  'https://bit.ly/3jOueGG',
  'https://bit.ly/3qYOtDm',
  'https://bit.ly/3wt11Ec',
  'https://bit.ly/3yvFg7X',
  'https://bit.ly/3ywzOla',
  'https://bit.ly/3wnASpW',
  'https://bit.ly/3jXSDto',
];

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: CustomScrollView(
        slivers: [
          CustomAppBar(),
          CustomGridView(),
          CustomListView(),
        ],
      ),
    );
  }
}

class CustomListView extends StatelessWidget {
  const CustomListView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverList(
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            return Padding(
              padding: const EdgeInsets.only(bottom: 8.0),
              child: Image.network(gridImages[index]),
            );
          },
          childCount: gridImages.length,
        ),
      ),
    );
  }
}

class CustomGridView extends StatelessWidget {
  const CustomGridView({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverPadding(
      padding: EdgeInsets.all(8.0),
      sliver: SliverGrid(
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 3,
          mainAxisSpacing: 10,
          crossAxisSpacing: 10,
          childAspectRatio: 1.0,
        ),
        delegate: SliverChildBuilderDelegate(
          (context, index) {
            return Container(
              width: 100,
              height: 100,
              child: Image.network(gridImages[index]),
            );
          },
          childCount: gridImages.length,
        ),
      ),
    );
  }
}

class CustomAppBar extends StatelessWidget {
  const CustomAppBar({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return SliverAppBar(
      backgroundColor: Colors.orange[300],
      forceElevated: true,
      pinned: false,
      snap: false,
      floating: true,
      expandedHeight: 172,
      flexibleSpace: FlexibleSpaceBar(
        title: Text(
          'Flutter',
          style: TextStyle(
            fontSize: 30,
            color: Colors.white,
            decoration: TextDecoration.underline,
          ),
        ),
        collapseMode: CollapseMode.parallax,
        background: Image.network('https://bit.ly/3x7J5Qt'),
      ),
    );
  }
}

Parallax App Bar in Flutter

JSON HTTP Requests in Dart

URL Timeouts in Dart

Detecting URL File Types in Dart

Paginated Lists in Dart

Requesting DELETE on APIs in Dart

Animated Containers in Flutter

Hiding Widgets in Flutter

Simple Opacity Animation in Flutter

Vignette Widget in Flutter

Drop Down Button Configuration and Usage in Flutter

Expandable List Items in Flutter

Infinite Scrolling in Flutter

Infinite Arrays in Dart

Custom Color Picker Component in Flutter

Displaying and Reacting to Switches in Flutter

Displaying Bottom Bars in Flutter

Displaying Buttons on AppBar in Flutter

Displaying Bottom Sheets in Flutter

Converting Enums to Radio Buttons in Flutter

Check Existence of Websites in Flutter

Images inside AlertDialog in Flutter

Returning Values from AlertDialog in Flutter

Simple Grid View in Flutter

Rendering Bullet Points in Flutter

Retrying Futures in Flutter

Containers as ClipOvals in Flutter

Rich Texts in Flutter

Wrapping Widgets in Flutter

Sweep Gradients in Flutter

Stream and StreamBuilder in Flutter

Blur Effect in Flutter

Convert Enums to Strings in Dart

Replacing Text in TextField in Flutter

Aspect Ratio in Flutter

Zoom and Pan in Flutter

Resizing Images in Flutter to Fit Screen Height

Validating URLs in Flutter

FrameBuilder for Network Images in Flutter

Adding Shadow to Icons in Flutter

Calculating Median of Lists in Dart

Generic Functions with Reduce in Dart

Passing Back Data From a Screen to the Previous One in Flutter

Flinging an Animation in Flutter

Fade Animations in Flutter

Throttling User Input in Flutter

Censoring TextFields in Flutter

Customizing TextButton in Flutter

Multiline TextFields in Flutter

Filtering TextField Input in Flutter

Focusing Manually on TextFields in Flutter

Data Streams Over HTTP/HTTPs in Dart

Catching Nonexistent Accessors or Methods in Dart

Using Expando in Dart

Implementing Custom Maps in Dart

Dynamically Calling Functions in Dart

Factory Constructors in Dart

Calculating the Sum of List Items in Dart

Removing Duplicate Strings in Lists in Dart (Case-Insensitive)

Implementing Range in Dart

Converting Lists to Maps in Dart

Implementing Hashable in Dart

Random Name Generator in Dart

Capturing Stack Traces in Dart Exceptions

Removing Duplicates from Lists in Dart

Optional Spread Operator in Dart

Calling Optional Functions in Dart

Odd-Even Sort in Dart

Implementing Zip and Tuples in Dart

Swapping Values in Lists with XOR in Dart

Waiting for Multiple Futures in Dart

Using Queues as Stacks in Dart

Custom Iterators in Dart

Iterables as Ranges and Transform in Dart

Errors vs Exceptions in Dart

Custom Annotations in Dart

Classes as Enums in Dart

Spread Operator in Collection Literals in Dart

StreamBuilder and StreamController in Dart

Almost Equal in Dart

Enum Associated Values in Dart

Implementing Comparable in Dart

Implementing Custom Integer Types in Dart

Custom Subscripts in Dart

Dart List Enumeration with Index

Applying Mixins to Other Mixins in Dart

Parameter Types in Dart

Custom Exceptions in Dart

rethrowing Exceptions in Dart

mixins and JSON Parsing in Dart

mixins vs abstract classes in Dart

Drawing Shapes in Flutter with LayoutBuilder, CustomPaint and CustomPainter

Generic Type Aliases in Dart

Callable Classes in Dart

Synchronous Generators in Dart

Implicit Interfaces in Dart

Did you know that in #Dart, every #class implicitly exports an #interface that can be #implemented (as opposed to #extended) by other classes? This is called "implicit interface".

Do you know how "const" constructors work in #Dart?

Did you know that in #Dart, it is actually preferred to use #async and #await over using raw #Futures?

In #Dart, you can use a combination of #Initializer #List plus default values for your class #member #fields to create elegant and handy convenience initializers

Did you know that in #Dart, you can extract elements of a certain type from your Lists using the #whereType #generic #function instead of calculating the #equality yourselves?

Do you know about #Type #Promotion in Dart?

"address" is an optional field of the "Person" class. If you look at the "doThis()" function you see that I'm saving the value of address in a local variable and then comparing it with null and then returning if it's null. The Dart compiler is intelligent enough to understand that after the if-statement, "address" is NOT null anymore since you've already compared it with null and returned from the function.

If you look at the "insteadOfThis" function, the first one, the Dart compiler cannot make the same assumption if you don't first store the value of address in a local variable. In that first function the Dart compiler, even after the if-statement, needs you to refer to address as an optional, using "address?" syntax.

The mechanism the Dart compiler uses in the "doThis()" function is called Type Promotion.

4 lines of #Dart code that include the #spread operator, #cascade #operator, #generics, #extensions, #private prefix and #getters

Functions as First Class Citizens in Dart

Download Details: 
Author: vandadnp
Source Code: https://github.com/vandadnp/flutter-tips-and-tricks

#flutter #dart #programming #developer 

Nat  Grady

Nat Grady

1658734620

Chromium-net-errors: Chromium Network Errors for Node.js

Chromium Network Errors

Provides Chromium network errors found in net_error_list.h as custom error classes that can be conveniently used in Node.js, Electron apps and browsers.

The errors correspond to the error codes that are provided in Electron's did-fail-load events of the WebContents class and the webview tag.

Features

  • No dependencies.
  • 100% test coverage.
  • ES6 build with import and export, and a CommonJS build. Your bundler can use the ES6 modules if it supports the "module" or "jsnext:main" directives in the package.json.
  • Daily cron-triggered checks for updates on net_error_list.h on Travis CI to always get the most up-to-date list of errors.

Installation

npm install chromium-net-errors --save
import * as chromiumNetErrors from 'chromium-net-errors';
// or
const chromiumNetErrors = require('chromium-net-errors');

Example Use in Electron

import { app, BrowserWindow } from 'electron';
import * as chromiumNetErrors from 'chromium-net-errors';

app.on('ready', () => {
  const win = new BrowserWindow({
    width: 800,
    height: 600,
  });

  win.webContents.on('did-fail-load', (event) => {
    try {
      const Err = chromiumNetErrors.getErrorByCode(event.errorCode);
      throw new Err();
    } catch (err) {
      if (err instanceof chromiumNetErrors.NameNotResolvedError) {
        console.error(`The name '${event.validatedURL}' could not be resolved:\n  ${err.message}`);
      } else {
        console.error(`Something went wrong while loading ${event.validatedURL}`);
      }
    }
  });

  win.loadURL('http://blablanotexist.com');
});

Usage

import * as chromiumNetErrors from 'chromium-net-errors';

Create New Errors

const err = new chromiumNetErrors.ConnectionTimedOutError();

console.log(err instanceof Error);
// true
console.log(err instanceof chromiumNetErrors.ChromiumNetError);
// true
console.log(err instanceof chromiumNetErrors.ConnectionTimedOutError);
// true
function thrower() {
  throw new chromiumNetErrors.ConnectionTimedOutError();
}

try {
  thrower();
} catch (err) {
  console.log(err instanceof Error);
  // true
  console.log(err instanceof chromiumNetErrors.ChromiumNetError);
  // true
  console.log(err instanceof chromiumNetErrors.ConnectionTimedOutError);
  // true
}

Get Error by errorCode

Get the class of an error by its errorCode.

const Err = chromiumNetErrors.getErrorByCode(-201);
const err = new Err();

console.log(err instanceof chromiumNetErrors.CertDateInvalidError);
// true

console.log(err.isCertificateError());
// true

console.log(err.type); 
// 'certificate'

console.log(err.message);
// The server responded with a certificate that, by our clock, appears to
// either not yet be valid or to have expired. This could mean:
// 
// 1. An attacker is presenting an old certificate for which they have
// managed to obtain the private key.
// 
// 2. The server is misconfigured and is not presenting a valid cert.
// 
// 3. Our clock is wrong.

Get Error by errorDescription

Get the class of an error by its errorDescription.

const Err = chromiumNetErrors.getErrorByDescription('CERT_DATE_INVALID');
const err = new Err();

console.log(err instanceof chromiumNetErrors.CertDateInvalidError);
// true

console.log(err.isCertificateError());
// true

console.log(err.type); 
// 'certificate'

console.log(err.message);
// The server responded with a certificate that, by our clock, appears to
// either not yet be valid or to have expired. This could mean:
// 
// 1. An attacker is presenting an old certificate for which they have
// managed to obtain the private key.
// 
// 2. The server is misconfigured and is not presenting a valid cert.
// 
// 3. Our clock is wrong.

Get All Errors

Get an array of all possible errors.

console.log(chromiumNetErrors.getErrors());

// [ { name: 'IoPendingError',
//     code: -1,
//     description: 'IO_PENDING',
//     type: 'system',
//     message: 'An asynchronous IO operation is not yet complete.  This usually does not\nindicate a fatal error.  Typically this error will be generated as a\nnotification to wait for some external notification that the IO operation\nfinally completed.' },
//   { name: 'FailedError',
//     code: -2,
//     description: 'FAILED',
//     type: 'system',
//     message: 'A generic failure occurred.' },
//   { name: 'AbortedError',
//     code: -3,
//     description: 'ABORTED',
//     type: 'system',
//     message: 'An operation was aborted (due to user action).' },
//   { name: 'InvalidArgumentError',
//     code: -4,
//     description: 'INVALID_ARGUMENT',
//     type: 'system',
//     message: 'An argument to the function is incorrect.' },
//   { name: 'InvalidHandleError',
//     code: -5,
//     description: 'INVALID_HANDLE',
//     type: 'system',
//     message: 'The handle or file descriptor is invalid.' },
//   ...
// ]

List of Errors

IoPendingError

An asynchronous IO operation is not yet complete. This usually does not indicate a fatal error. Typically this error will be generated as a notification to wait for some external notification that the IO operation finally completed.

  • Name: IoPendingError
  • Code: -1
  • Description: IO_PENDING
  • Type: system
const err = new chromiumNetErrors.IoPendingError();
// or
const Err = chromiumNetErrors.getErrorByCode(-1);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('IO_PENDING');
const err = new Err();

FailedError

A generic failure occurred.

  • Name: FailedError
  • Code: -2
  • Description: FAILED
  • Type: system
const err = new chromiumNetErrors.FailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-2);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FAILED');
const err = new Err();

AbortedError

An operation was aborted (due to user action).

  • Name: AbortedError
  • Code: -3
  • Description: ABORTED
  • Type: system
const err = new chromiumNetErrors.AbortedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-3);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ABORTED');
const err = new Err();

InvalidArgumentError

An argument to the function is incorrect.

  • Name: InvalidArgumentError
  • Code: -4
  • Description: INVALID_ARGUMENT
  • Type: system
const err = new chromiumNetErrors.InvalidArgumentError();
// or
const Err = chromiumNetErrors.getErrorByCode(-4);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_ARGUMENT');
const err = new Err();

InvalidHandleError

The handle or file descriptor is invalid.

  • Name: InvalidHandleError
  • Code: -5
  • Description: INVALID_HANDLE
  • Type: system
const err = new chromiumNetErrors.InvalidHandleError();
// or
const Err = chromiumNetErrors.getErrorByCode(-5);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_HANDLE');
const err = new Err();

FileNotFoundError

The file or directory cannot be found.

  • Name: FileNotFoundError
  • Code: -6
  • Description: FILE_NOT_FOUND
  • Type: system
const err = new chromiumNetErrors.FileNotFoundError();
// or
const Err = chromiumNetErrors.getErrorByCode(-6);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FILE_NOT_FOUND');
const err = new Err();

TimedOutError

An operation timed out.

  • Name: TimedOutError
  • Code: -7
  • Description: TIMED_OUT
  • Type: system
const err = new chromiumNetErrors.TimedOutError();
// or
const Err = chromiumNetErrors.getErrorByCode(-7);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TIMED_OUT');
const err = new Err();

FileTooBigError

The file is too large.

  • Name: FileTooBigError
  • Code: -8
  • Description: FILE_TOO_BIG
  • Type: system
const err = new chromiumNetErrors.FileTooBigError();
// or
const Err = chromiumNetErrors.getErrorByCode(-8);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FILE_TOO_BIG');
const err = new Err();

UnexpectedError

An unexpected error. This may be caused by a programming mistake or an invalid assumption.

  • Name: UnexpectedError
  • Code: -9
  • Description: UNEXPECTED
  • Type: system
const err = new chromiumNetErrors.UnexpectedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-9);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNEXPECTED');
const err = new Err();

AccessDeniedError

Permission to access a resource, other than the network, was denied.

  • Name: AccessDeniedError
  • Code: -10
  • Description: ACCESS_DENIED
  • Type: system
const err = new chromiumNetErrors.AccessDeniedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-10);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ACCESS_DENIED');
const err = new Err();

NotImplementedError

The operation failed because of unimplemented functionality.

  • Name: NotImplementedError
  • Code: -11
  • Description: NOT_IMPLEMENTED
  • Type: system
const err = new chromiumNetErrors.NotImplementedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-11);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NOT_IMPLEMENTED');
const err = new Err();

InsufficientResourcesError

There were not enough resources to complete the operation.

  • Name: InsufficientResourcesError
  • Code: -12
  • Description: INSUFFICIENT_RESOURCES
  • Type: system
const err = new chromiumNetErrors.InsufficientResourcesError();
// or
const Err = chromiumNetErrors.getErrorByCode(-12);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INSUFFICIENT_RESOURCES');
const err = new Err();

OutOfMemoryError

Memory allocation failed.

  • Name: OutOfMemoryError
  • Code: -13
  • Description: OUT_OF_MEMORY
  • Type: system
const err = new chromiumNetErrors.OutOfMemoryError();
// or
const Err = chromiumNetErrors.getErrorByCode(-13);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('OUT_OF_MEMORY');
const err = new Err();

UploadFileChangedError

The file upload failed because the file's modification time was different from the expectation.

  • Name: UploadFileChangedError
  • Code: -14
  • Description: UPLOAD_FILE_CHANGED
  • Type: system
const err = new chromiumNetErrors.UploadFileChangedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-14);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UPLOAD_FILE_CHANGED');
const err = new Err();

SocketNotConnectedError

The socket is not connected.

  • Name: SocketNotConnectedError
  • Code: -15
  • Description: SOCKET_NOT_CONNECTED
  • Type: system
const err = new chromiumNetErrors.SocketNotConnectedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-15);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKET_NOT_CONNECTED');
const err = new Err();

FileExistsError

The file already exists.

  • Name: FileExistsError
  • Code: -16
  • Description: FILE_EXISTS
  • Type: system
const err = new chromiumNetErrors.FileExistsError();
// or
const Err = chromiumNetErrors.getErrorByCode(-16);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FILE_EXISTS');
const err = new Err();

FilePathTooLongError

The path or file name is too long.

  • Name: FilePathTooLongError
  • Code: -17
  • Description: FILE_PATH_TOO_LONG
  • Type: system
const err = new chromiumNetErrors.FilePathTooLongError();
// or
const Err = chromiumNetErrors.getErrorByCode(-17);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FILE_PATH_TOO_LONG');
const err = new Err();

FileNoSpaceError

Not enough room left on the disk.

  • Name: FileNoSpaceError
  • Code: -18
  • Description: FILE_NO_SPACE
  • Type: system
const err = new chromiumNetErrors.FileNoSpaceError();
// or
const Err = chromiumNetErrors.getErrorByCode(-18);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FILE_NO_SPACE');
const err = new Err();

FileVirusInfectedError

The file has a virus.

  • Name: FileVirusInfectedError
  • Code: -19
  • Description: FILE_VIRUS_INFECTED
  • Type: system
const err = new chromiumNetErrors.FileVirusInfectedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-19);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FILE_VIRUS_INFECTED');
const err = new Err();

BlockedByClientError

The client chose to block the request.

  • Name: BlockedByClientError
  • Code: -20
  • Description: BLOCKED_BY_CLIENT
  • Type: system
const err = new chromiumNetErrors.BlockedByClientError();
// or
const Err = chromiumNetErrors.getErrorByCode(-20);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('BLOCKED_BY_CLIENT');
const err = new Err();

NetworkChangedError

The network changed.

  • Name: NetworkChangedError
  • Code: -21
  • Description: NETWORK_CHANGED
  • Type: system
const err = new chromiumNetErrors.NetworkChangedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-21);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NETWORK_CHANGED');
const err = new Err();

BlockedByAdministratorError

The request was blocked by the URL block list configured by the domain administrator.

  • Name: BlockedByAdministratorError
  • Code: -22
  • Description: BLOCKED_BY_ADMINISTRATOR
  • Type: system
const err = new chromiumNetErrors.BlockedByAdministratorError();
// or
const Err = chromiumNetErrors.getErrorByCode(-22);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('BLOCKED_BY_ADMINISTRATOR');
const err = new Err();

SocketIsConnectedError

The socket is already connected.

  • Name: SocketIsConnectedError
  • Code: -23
  • Description: SOCKET_IS_CONNECTED
  • Type: system
const err = new chromiumNetErrors.SocketIsConnectedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-23);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKET_IS_CONNECTED');
const err = new Err();

BlockedEnrollmentCheckPendingError

The request was blocked because the forced reenrollment check is still pending. This error can only occur on ChromeOS. The error can be emitted by code in chrome/browser/policy/policy_helpers.cc.

  • Name: BlockedEnrollmentCheckPendingError
  • Code: -24
  • Description: BLOCKED_ENROLLMENT_CHECK_PENDING
  • Type: system
const err = new chromiumNetErrors.BlockedEnrollmentCheckPendingError();
// or
const Err = chromiumNetErrors.getErrorByCode(-24);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('BLOCKED_ENROLLMENT_CHECK_PENDING');
const err = new Err();

UploadStreamRewindNotSupportedError

The upload failed because the upload stream needed to be re-read, due to a retry or a redirect, but the upload stream doesn't support that operation.

  • Name: UploadStreamRewindNotSupportedError
  • Code: -25
  • Description: UPLOAD_STREAM_REWIND_NOT_SUPPORTED
  • Type: system
const err = new chromiumNetErrors.UploadStreamRewindNotSupportedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-25);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UPLOAD_STREAM_REWIND_NOT_SUPPORTED');
const err = new Err();

ContextShutDownError

The request failed because the URLRequestContext is shutting down, or has been shut down.

  • Name: ContextShutDownError
  • Code: -26
  • Description: CONTEXT_SHUT_DOWN
  • Type: system
const err = new chromiumNetErrors.ContextShutDownError();
// or
const Err = chromiumNetErrors.getErrorByCode(-26);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONTEXT_SHUT_DOWN');
const err = new Err();

BlockedByResponseError

The request failed because the response was delivered along with requirements which are not met ('X-Frame-Options' and 'Content-Security-Policy' ancestor checks and 'Cross-Origin-Resource-Policy', for instance).

  • Name: BlockedByResponseError
  • Code: -27
  • Description: BLOCKED_BY_RESPONSE
  • Type: system
const err = new chromiumNetErrors.BlockedByResponseError();
// or
const Err = chromiumNetErrors.getErrorByCode(-27);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('BLOCKED_BY_RESPONSE');
const err = new Err();

CleartextNotPermittedError

The request was blocked by system policy disallowing some or all cleartext requests. Used for NetworkSecurityPolicy on Android.

  • Name: CleartextNotPermittedError
  • Code: -29
  • Description: CLEARTEXT_NOT_PERMITTED
  • Type: system
const err = new chromiumNetErrors.CleartextNotPermittedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-29);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CLEARTEXT_NOT_PERMITTED');
const err = new Err();

BlockedByCspError

The request was blocked by a Content Security Policy

  • Name: BlockedByCspError
  • Code: -30
  • Description: BLOCKED_BY_CSP
  • Type: system
const err = new chromiumNetErrors.BlockedByCspError();
// or
const Err = chromiumNetErrors.getErrorByCode(-30);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('BLOCKED_BY_CSP');
const err = new Err();

H2OrQuicRequiredError

The request was blocked because of no H/2 or QUIC session.

  • Name: H2OrQuicRequiredError
  • Code: -31
  • Description: H2_OR_QUIC_REQUIRED
  • Type: system
const err = new chromiumNetErrors.H2OrQuicRequiredError();
// or
const Err = chromiumNetErrors.getErrorByCode(-31);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('H2_OR_QUIC_REQUIRED');
const err = new Err();

ConnectionClosedError

A connection was closed (corresponding to a TCP FIN).

  • Name: ConnectionClosedError
  • Code: -100
  • Description: CONNECTION_CLOSED
  • Type: connection
const err = new chromiumNetErrors.ConnectionClosedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-100);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONNECTION_CLOSED');
const err = new Err();

ConnectionResetError

A connection was reset (corresponding to a TCP RST).

  • Name: ConnectionResetError
  • Code: -101
  • Description: CONNECTION_RESET
  • Type: connection
const err = new chromiumNetErrors.ConnectionResetError();
// or
const Err = chromiumNetErrors.getErrorByCode(-101);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONNECTION_RESET');
const err = new Err();

ConnectionRefusedError

A connection attempt was refused.

  • Name: ConnectionRefusedError
  • Code: -102
  • Description: CONNECTION_REFUSED
  • Type: connection
const err = new chromiumNetErrors.ConnectionRefusedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-102);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONNECTION_REFUSED');
const err = new Err();

ConnectionAbortedError

A connection timed out as a result of not receiving an ACK for data sent. This can include a FIN packet that did not get ACK'd.

  • Name: ConnectionAbortedError
  • Code: -103
  • Description: CONNECTION_ABORTED
  • Type: connection
const err = new chromiumNetErrors.ConnectionAbortedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-103);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONNECTION_ABORTED');
const err = new Err();

ConnectionFailedError

A connection attempt failed.

  • Name: ConnectionFailedError
  • Code: -104
  • Description: CONNECTION_FAILED
  • Type: connection
const err = new chromiumNetErrors.ConnectionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-104);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONNECTION_FAILED');
const err = new Err();

NameNotResolvedError

The host name could not be resolved.

  • Name: NameNotResolvedError
  • Code: -105
  • Description: NAME_NOT_RESOLVED
  • Type: connection
const err = new chromiumNetErrors.NameNotResolvedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-105);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NAME_NOT_RESOLVED');
const err = new Err();

InternetDisconnectedError

The Internet connection has been lost.

  • Name: InternetDisconnectedError
  • Code: -106
  • Description: INTERNET_DISCONNECTED
  • Type: connection
const err = new chromiumNetErrors.InternetDisconnectedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-106);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INTERNET_DISCONNECTED');
const err = new Err();

SslProtocolError

An SSL protocol error occurred.

  • Name: SslProtocolError
  • Code: -107
  • Description: SSL_PROTOCOL_ERROR
  • Type: connection
const err = new chromiumNetErrors.SslProtocolError();
// or
const Err = chromiumNetErrors.getErrorByCode(-107);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_PROTOCOL_ERROR');
const err = new Err();

AddressInvalidError

The IP address or port number is invalid (e.g., cannot connect to the IP address 0 or the port 0).

  • Name: AddressInvalidError
  • Code: -108
  • Description: ADDRESS_INVALID
  • Type: connection
const err = new chromiumNetErrors.AddressInvalidError();
// or
const Err = chromiumNetErrors.getErrorByCode(-108);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ADDRESS_INVALID');
const err = new Err();

AddressUnreachableError

The IP address is unreachable. This usually means that there is no route to the specified host or network.

  • Name: AddressUnreachableError
  • Code: -109
  • Description: ADDRESS_UNREACHABLE
  • Type: connection
const err = new chromiumNetErrors.AddressUnreachableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-109);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ADDRESS_UNREACHABLE');
const err = new Err();

SslClientAuthCertNeededError

The server requested a client certificate for SSL client authentication.

  • Name: SslClientAuthCertNeededError
  • Code: -110
  • Description: SSL_CLIENT_AUTH_CERT_NEEDED
  • Type: connection
const err = new chromiumNetErrors.SslClientAuthCertNeededError();
// or
const Err = chromiumNetErrors.getErrorByCode(-110);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_CLIENT_AUTH_CERT_NEEDED');
const err = new Err();

TunnelConnectionFailedError

A tunnel connection through the proxy could not be established.

  • Name: TunnelConnectionFailedError
  • Code: -111
  • Description: TUNNEL_CONNECTION_FAILED
  • Type: connection
const err = new chromiumNetErrors.TunnelConnectionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-111);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TUNNEL_CONNECTION_FAILED');
const err = new Err();

NoSslVersionsEnabledError

No SSL protocol versions are enabled.

  • Name: NoSslVersionsEnabledError
  • Code: -112
  • Description: NO_SSL_VERSIONS_ENABLED
  • Type: connection
const err = new chromiumNetErrors.NoSslVersionsEnabledError();
// or
const Err = chromiumNetErrors.getErrorByCode(-112);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NO_SSL_VERSIONS_ENABLED');
const err = new Err();

SslVersionOrCipherMismatchError

The client and server don't support a common SSL protocol version or cipher suite.

  • Name: SslVersionOrCipherMismatchError
  • Code: -113
  • Description: SSL_VERSION_OR_CIPHER_MISMATCH
  • Type: connection
const err = new chromiumNetErrors.SslVersionOrCipherMismatchError();
// or
const Err = chromiumNetErrors.getErrorByCode(-113);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_VERSION_OR_CIPHER_MISMATCH');
const err = new Err();

SslRenegotiationRequestedError

The server requested a renegotiation (rehandshake).

  • Name: SslRenegotiationRequestedError
  • Code: -114
  • Description: SSL_RENEGOTIATION_REQUESTED
  • Type: connection
const err = new chromiumNetErrors.SslRenegotiationRequestedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-114);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_RENEGOTIATION_REQUESTED');
const err = new Err();

ProxyAuthUnsupportedError

The proxy requested authentication (for tunnel establishment) with an unsupported method.

  • Name: ProxyAuthUnsupportedError
  • Code: -115
  • Description: PROXY_AUTH_UNSUPPORTED
  • Type: connection
const err = new chromiumNetErrors.ProxyAuthUnsupportedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-115);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PROXY_AUTH_UNSUPPORTED');
const err = new Err();

CertErrorInSslRenegotiationError

During SSL renegotiation (rehandshake), the server sent a certificate with an error.

Note: this error is not in the -2xx range so that it won't be handled as a certificate error.

  • Name: CertErrorInSslRenegotiationError
  • Code: -116
  • Description: CERT_ERROR_IN_SSL_RENEGOTIATION
  • Type: connection
const err = new chromiumNetErrors.CertErrorInSslRenegotiationError();
// or
const Err = chromiumNetErrors.getErrorByCode(-116);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_ERROR_IN_SSL_RENEGOTIATION');
const err = new Err();

BadSslClientAuthCertError

The SSL handshake failed because of a bad or missing client certificate.

  • Name: BadSslClientAuthCertError
  • Code: -117
  • Description: BAD_SSL_CLIENT_AUTH_CERT
  • Type: connection
const err = new chromiumNetErrors.BadSslClientAuthCertError();
// or
const Err = chromiumNetErrors.getErrorByCode(-117);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('BAD_SSL_CLIENT_AUTH_CERT');
const err = new Err();

ConnectionTimedOutError

A connection attempt timed out.

  • Name: ConnectionTimedOutError
  • Code: -118
  • Description: CONNECTION_TIMED_OUT
  • Type: connection
const err = new chromiumNetErrors.ConnectionTimedOutError();
// or
const Err = chromiumNetErrors.getErrorByCode(-118);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONNECTION_TIMED_OUT');
const err = new Err();

HostResolverQueueTooLargeError

There are too many pending DNS resolves, so a request in the queue was aborted.

  • Name: HostResolverQueueTooLargeError
  • Code: -119
  • Description: HOST_RESOLVER_QUEUE_TOO_LARGE
  • Type: connection
const err = new chromiumNetErrors.HostResolverQueueTooLargeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-119);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HOST_RESOLVER_QUEUE_TOO_LARGE');
const err = new Err();

SocksConnectionFailedError

Failed establishing a connection to the SOCKS proxy server for a target host.

  • Name: SocksConnectionFailedError
  • Code: -120
  • Description: SOCKS_CONNECTION_FAILED
  • Type: connection
const err = new chromiumNetErrors.SocksConnectionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-120);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKS_CONNECTION_FAILED');
const err = new Err();

SocksConnectionHostUnreachableError

The SOCKS proxy server failed establishing connection to the target host because that host is unreachable.

  • Name: SocksConnectionHostUnreachableError
  • Code: -121
  • Description: SOCKS_CONNECTION_HOST_UNREACHABLE
  • Type: connection
const err = new chromiumNetErrors.SocksConnectionHostUnreachableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-121);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKS_CONNECTION_HOST_UNREACHABLE');
const err = new Err();

AlpnNegotiationFailedError

The request to negotiate an alternate protocol failed.

  • Name: AlpnNegotiationFailedError
  • Code: -122
  • Description: ALPN_NEGOTIATION_FAILED
  • Type: connection
const err = new chromiumNetErrors.AlpnNegotiationFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-122);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ALPN_NEGOTIATION_FAILED');
const err = new Err();

SslNoRenegotiationError

The peer sent an SSL no_renegotiation alert message.

  • Name: SslNoRenegotiationError
  • Code: -123
  • Description: SSL_NO_RENEGOTIATION
  • Type: connection
const err = new chromiumNetErrors.SslNoRenegotiationError();
// or
const Err = chromiumNetErrors.getErrorByCode(-123);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_NO_RENEGOTIATION');
const err = new Err();

WinsockUnexpectedWrittenBytesError

Winsock sometimes reports more data written than passed. This is probably due to a broken LSP.

  • Name: WinsockUnexpectedWrittenBytesError
  • Code: -124
  • Description: WINSOCK_UNEXPECTED_WRITTEN_BYTES
  • Type: connection
const err = new chromiumNetErrors.WinsockUnexpectedWrittenBytesError();
// or
const Err = chromiumNetErrors.getErrorByCode(-124);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('WINSOCK_UNEXPECTED_WRITTEN_BYTES');
const err = new Err();

SslDecompressionFailureAlertError

An SSL peer sent us a fatal decompression_failure alert. This typically occurs when a peer selects DEFLATE compression in the mistaken belief that it supports it.

  • Name: SslDecompressionFailureAlertError
  • Code: -125
  • Description: SSL_DECOMPRESSION_FAILURE_ALERT
  • Type: connection
const err = new chromiumNetErrors.SslDecompressionFailureAlertError();
// or
const Err = chromiumNetErrors.getErrorByCode(-125);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_DECOMPRESSION_FAILURE_ALERT');
const err = new Err();

SslBadRecordMacAlertError

An SSL peer sent us a fatal bad_record_mac alert. This has been observed from servers with buggy DEFLATE support.

  • Name: SslBadRecordMacAlertError
  • Code: -126
  • Description: SSL_BAD_RECORD_MAC_ALERT
  • Type: connection
const err = new chromiumNetErrors.SslBadRecordMacAlertError();
// or
const Err = chromiumNetErrors.getErrorByCode(-126);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_BAD_RECORD_MAC_ALERT');
const err = new Err();

ProxyAuthRequestedError

The proxy requested authentication (for tunnel establishment).

  • Name: ProxyAuthRequestedError
  • Code: -127
  • Description: PROXY_AUTH_REQUESTED
  • Type: connection
const err = new chromiumNetErrors.ProxyAuthRequestedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-127);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PROXY_AUTH_REQUESTED');
const err = new Err();

ProxyConnectionFailedError

Could not create a connection to the proxy server. An error occurred either in resolving its name, or in connecting a socket to it. Note that this does NOT include failures during the actual "CONNECT" method of an HTTP proxy.

  • Name: ProxyConnectionFailedError
  • Code: -130
  • Description: PROXY_CONNECTION_FAILED
  • Type: connection
const err = new chromiumNetErrors.ProxyConnectionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-130);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PROXY_CONNECTION_FAILED');
const err = new Err();

MandatoryProxyConfigurationFailedError

A mandatory proxy configuration could not be used. Currently this means that a mandatory PAC script could not be fetched, parsed or executed.

  • Name: MandatoryProxyConfigurationFailedError
  • Code: -131
  • Description: MANDATORY_PROXY_CONFIGURATION_FAILED
  • Type: connection
const err = new chromiumNetErrors.MandatoryProxyConfigurationFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-131);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('MANDATORY_PROXY_CONFIGURATION_FAILED');
const err = new Err();

PreconnectMaxSocketLimitError

We've hit the max socket limit for the socket pool while preconnecting. We don't bother trying to preconnect more sockets.

  • Name: PreconnectMaxSocketLimitError
  • Code: -133
  • Description: PRECONNECT_MAX_SOCKET_LIMIT
  • Type: connection
const err = new chromiumNetErrors.PreconnectMaxSocketLimitError();
// or
const Err = chromiumNetErrors.getErrorByCode(-133);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PRECONNECT_MAX_SOCKET_LIMIT');
const err = new Err();

SslClientAuthPrivateKeyAccessDeniedError

The permission to use the SSL client certificate's private key was denied.

  • Name: SslClientAuthPrivateKeyAccessDeniedError
  • Code: -134
  • Description: SSL_CLIENT_AUTH_PRIVATE_KEY_ACCESS_DENIED
  • Type: connection
const err = new chromiumNetErrors.SslClientAuthPrivateKeyAccessDeniedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-134);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_CLIENT_AUTH_PRIVATE_KEY_ACCESS_DENIED');
const err = new Err();

SslClientAuthCertNoPrivateKeyError

The SSL client certificate has no private key.

  • Name: SslClientAuthCertNoPrivateKeyError
  • Code: -135
  • Description: SSL_CLIENT_AUTH_CERT_NO_PRIVATE_KEY
  • Type: connection
const err = new chromiumNetErrors.SslClientAuthCertNoPrivateKeyError();
// or
const Err = chromiumNetErrors.getErrorByCode(-135);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_CLIENT_AUTH_CERT_NO_PRIVATE_KEY');
const err = new Err();

ProxyCertificateInvalidError

The certificate presented by the HTTPS Proxy was invalid.

  • Name: ProxyCertificateInvalidError
  • Code: -136
  • Description: PROXY_CERTIFICATE_INVALID
  • Type: connection
const err = new chromiumNetErrors.ProxyCertificateInvalidError();
// or
const Err = chromiumNetErrors.getErrorByCode(-136);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PROXY_CERTIFICATE_INVALID');
const err = new Err();

NameResolutionFailedError

An error occurred when trying to do a name resolution (DNS).

  • Name: NameResolutionFailedError
  • Code: -137
  • Description: NAME_RESOLUTION_FAILED
  • Type: connection
const err = new chromiumNetErrors.NameResolutionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-137);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NAME_RESOLUTION_FAILED');
const err = new Err();

NetworkAccessDeniedError

Permission to access the network was denied. This is used to distinguish errors that were most likely caused by a firewall from other access denied errors. See also ERR_ACCESS_DENIED.

  • Name: NetworkAccessDeniedError
  • Code: -138
  • Description: NETWORK_ACCESS_DENIED
  • Type: connection
const err = new chromiumNetErrors.NetworkAccessDeniedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-138);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NETWORK_ACCESS_DENIED');
const err = new Err();

TemporarilyThrottledError

The request throttler module cancelled this request to avoid DDOS.

  • Name: TemporarilyThrottledError
  • Code: -139
  • Description: TEMPORARILY_THROTTLED
  • Type: connection
const err = new chromiumNetErrors.TemporarilyThrottledError();
// or
const Err = chromiumNetErrors.getErrorByCode(-139);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TEMPORARILY_THROTTLED');
const err = new Err();

HttpsProxyTunnelResponseRedirectError

A request to create an SSL tunnel connection through the HTTPS proxy received a 302 (temporary redirect) response. The response body might include a description of why the request failed.

TODO(https://crbug.com/928551): This is deprecated and should not be used by new code.

  • Name: HttpsProxyTunnelResponseRedirectError
  • Code: -140
  • Description: HTTPS_PROXY_TUNNEL_RESPONSE_REDIRECT
  • Type: connection
const err = new chromiumNetErrors.HttpsProxyTunnelResponseRedirectError();
// or
const Err = chromiumNetErrors.getErrorByCode(-140);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTPS_PROXY_TUNNEL_RESPONSE_REDIRECT');
const err = new Err();

SslClientAuthSignatureFailedError

We were unable to sign the CertificateVerify data of an SSL client auth handshake with the client certificate's private key.

Possible causes for this include the user implicitly or explicitly denying access to the private key, the private key may not be valid for signing, the key may be relying on a cached handle which is no longer valid, or the CSP won't allow arbitrary data to be signed.

  • Name: SslClientAuthSignatureFailedError
  • Code: -141
  • Description: SSL_CLIENT_AUTH_SIGNATURE_FAILED
  • Type: connection
const err = new chromiumNetErrors.SslClientAuthSignatureFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-141);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_CLIENT_AUTH_SIGNATURE_FAILED');
const err = new Err();

MsgTooBigError

The message was too large for the transport. (for example a UDP message which exceeds size threshold).

  • Name: MsgTooBigError
  • Code: -142
  • Description: MSG_TOO_BIG
  • Type: connection
const err = new chromiumNetErrors.MsgTooBigError();
// or
const Err = chromiumNetErrors.getErrorByCode(-142);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('MSG_TOO_BIG');
const err = new Err();

WsProtocolError

Websocket protocol error. Indicates that we are terminating the connection due to a malformed frame or other protocol violation.

  • Name: WsProtocolError
  • Code: -145
  • Description: WS_PROTOCOL_ERROR
  • Type: connection
const err = new chromiumNetErrors.WsProtocolError();
// or
const Err = chromiumNetErrors.getErrorByCode(-145);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('WS_PROTOCOL_ERROR');
const err = new Err();

AddressInUseError

Returned when attempting to bind an address that is already in use.

  • Name: AddressInUseError
  • Code: -147
  • Description: ADDRESS_IN_USE
  • Type: connection
const err = new chromiumNetErrors.AddressInUseError();
// or
const Err = chromiumNetErrors.getErrorByCode(-147);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ADDRESS_IN_USE');
const err = new Err();

SslHandshakeNotCompletedError

An operation failed because the SSL handshake has not completed.

  • Name: SslHandshakeNotCompletedError
  • Code: -148
  • Description: SSL_HANDSHAKE_NOT_COMPLETED
  • Type: connection
const err = new chromiumNetErrors.SslHandshakeNotCompletedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-148);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_HANDSHAKE_NOT_COMPLETED');
const err = new Err();

SslBadPeerPublicKeyError

SSL peer's public key is invalid.

  • Name: SslBadPeerPublicKeyError
  • Code: -149
  • Description: SSL_BAD_PEER_PUBLIC_KEY
  • Type: connection
const err = new chromiumNetErrors.SslBadPeerPublicKeyError();
// or
const Err = chromiumNetErrors.getErrorByCode(-149);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_BAD_PEER_PUBLIC_KEY');
const err = new Err();

SslPinnedKeyNotInCertChainError

The certificate didn't match the built-in public key pins for the host name. The pins are set in net/http/transport_security_state.cc and require that one of a set of public keys exist on the path from the leaf to the root.

  • Name: SslPinnedKeyNotInCertChainError
  • Code: -150
  • Description: SSL_PINNED_KEY_NOT_IN_CERT_CHAIN
  • Type: connection
const err = new chromiumNetErrors.SslPinnedKeyNotInCertChainError();
// or
const Err = chromiumNetErrors.getErrorByCode(-150);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_PINNED_KEY_NOT_IN_CERT_CHAIN');
const err = new Err();

ClientAuthCertTypeUnsupportedError

Server request for client certificate did not contain any types we support.

  • Name: ClientAuthCertTypeUnsupportedError
  • Code: -151
  • Description: CLIENT_AUTH_CERT_TYPE_UNSUPPORTED
  • Type: connection
const err = new chromiumNetErrors.ClientAuthCertTypeUnsupportedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-151);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CLIENT_AUTH_CERT_TYPE_UNSUPPORTED');
const err = new Err();

SslDecryptErrorAlertError

An SSL peer sent us a fatal decrypt_error alert. This typically occurs when a peer could not correctly verify a signature (in CertificateVerify or ServerKeyExchange) or validate a Finished message.

  • Name: SslDecryptErrorAlertError
  • Code: -153
  • Description: SSL_DECRYPT_ERROR_ALERT
  • Type: connection
const err = new chromiumNetErrors.SslDecryptErrorAlertError();
// or
const Err = chromiumNetErrors.getErrorByCode(-153);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_DECRYPT_ERROR_ALERT');
const err = new Err();

WsThrottleQueueTooLargeError

There are too many pending WebSocketJob instances, so the new job was not pushed to the queue.

  • Name: WsThrottleQueueTooLargeError
  • Code: -154
  • Description: WS_THROTTLE_QUEUE_TOO_LARGE
  • Type: connection
const err = new chromiumNetErrors.WsThrottleQueueTooLargeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-154);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('WS_THROTTLE_QUEUE_TOO_LARGE');
const err = new Err();

SslServerCertChangedError

The SSL server certificate changed in a renegotiation.

  • Name: SslServerCertChangedError
  • Code: -156
  • Description: SSL_SERVER_CERT_CHANGED
  • Type: connection
const err = new chromiumNetErrors.SslServerCertChangedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-156);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_SERVER_CERT_CHANGED');
const err = new Err();

SslUnrecognizedNameAlertError

The SSL server sent us a fatal unrecognized_name alert.

  • Name: SslUnrecognizedNameAlertError
  • Code: -159
  • Description: SSL_UNRECOGNIZED_NAME_ALERT
  • Type: connection
const err = new chromiumNetErrors.SslUnrecognizedNameAlertError();
// or
const Err = chromiumNetErrors.getErrorByCode(-159);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_UNRECOGNIZED_NAME_ALERT');
const err = new Err();

SocketSetReceiveBufferSizeError

Failed to set the socket's receive buffer size as requested.

  • Name: SocketSetReceiveBufferSizeError
  • Code: -160
  • Description: SOCKET_SET_RECEIVE_BUFFER_SIZE_ERROR
  • Type: connection
const err = new chromiumNetErrors.SocketSetReceiveBufferSizeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-160);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKET_SET_RECEIVE_BUFFER_SIZE_ERROR');
const err = new Err();

SocketSetSendBufferSizeError

Failed to set the socket's send buffer size as requested.

  • Name: SocketSetSendBufferSizeError
  • Code: -161
  • Description: SOCKET_SET_SEND_BUFFER_SIZE_ERROR
  • Type: connection
const err = new chromiumNetErrors.SocketSetSendBufferSizeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-161);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKET_SET_SEND_BUFFER_SIZE_ERROR');
const err = new Err();

SocketReceiveBufferSizeUnchangeableError

Failed to set the socket's receive buffer size as requested, despite success return code from setsockopt.

  • Name: SocketReceiveBufferSizeUnchangeableError
  • Code: -162
  • Description: SOCKET_RECEIVE_BUFFER_SIZE_UNCHANGEABLE
  • Type: connection
const err = new chromiumNetErrors.SocketReceiveBufferSizeUnchangeableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-162);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKET_RECEIVE_BUFFER_SIZE_UNCHANGEABLE');
const err = new Err();

SocketSendBufferSizeUnchangeableError

Failed to set the socket's send buffer size as requested, despite success return code from setsockopt.

  • Name: SocketSendBufferSizeUnchangeableError
  • Code: -163
  • Description: SOCKET_SEND_BUFFER_SIZE_UNCHANGEABLE
  • Type: connection
const err = new chromiumNetErrors.SocketSendBufferSizeUnchangeableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-163);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SOCKET_SEND_BUFFER_SIZE_UNCHANGEABLE');
const err = new Err();

SslClientAuthCertBadFormatError

Failed to import a client certificate from the platform store into the SSL library.

  • Name: SslClientAuthCertBadFormatError
  • Code: -164
  • Description: SSL_CLIENT_AUTH_CERT_BAD_FORMAT
  • Type: connection
const err = new chromiumNetErrors.SslClientAuthCertBadFormatError();
// or
const Err = chromiumNetErrors.getErrorByCode(-164);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_CLIENT_AUTH_CERT_BAD_FORMAT');
const err = new Err();

IcannNameCollisionError

Resolving a hostname to an IP address list included the IPv4 address "127.0.53.53". This is a special IP address which ICANN has recommended to indicate there was a name collision, and alert admins to a potential problem.

  • Name: IcannNameCollisionError
  • Code: -166
  • Description: ICANN_NAME_COLLISION
  • Type: connection
const err = new chromiumNetErrors.IcannNameCollisionError();
// or
const Err = chromiumNetErrors.getErrorByCode(-166);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ICANN_NAME_COLLISION');
const err = new Err();

SslServerCertBadFormatError

The SSL server presented a certificate which could not be decoded. This is not a certificate error code as no X509Certificate object is available. This error is fatal.

  • Name: SslServerCertBadFormatError
  • Code: -167
  • Description: SSL_SERVER_CERT_BAD_FORMAT
  • Type: connection
const err = new chromiumNetErrors.SslServerCertBadFormatError();
// or
const Err = chromiumNetErrors.getErrorByCode(-167);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_SERVER_CERT_BAD_FORMAT');
const err = new Err();

CtSthParsingFailedError

Certificate Transparency: Received a signed tree head that failed to parse.

  • Name: CtSthParsingFailedError
  • Code: -168
  • Description: CT_STH_PARSING_FAILED
  • Type: connection
const err = new chromiumNetErrors.CtSthParsingFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-168);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CT_STH_PARSING_FAILED');
const err = new Err();

CtSthIncompleteError

Certificate Transparency: Received a signed tree head whose JSON parsing was OK but was missing some of the fields.

  • Name: CtSthIncompleteError
  • Code: -169
  • Description: CT_STH_INCOMPLETE
  • Type: connection
const err = new chromiumNetErrors.CtSthIncompleteError();
// or
const Err = chromiumNetErrors.getErrorByCode(-169);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CT_STH_INCOMPLETE');
const err = new Err();

UnableToReuseConnectionForProxyAuthError

The attempt to reuse a connection to send proxy auth credentials failed before the AuthController was used to generate credentials. The caller should reuse the controller with a new connection. This error is only used internally by the network stack.

  • Name: UnableToReuseConnectionForProxyAuthError
  • Code: -170
  • Description: UNABLE_TO_REUSE_CONNECTION_FOR_PROXY_AUTH
  • Type: connection
const err = new chromiumNetErrors.UnableToReuseConnectionForProxyAuthError();
// or
const Err = chromiumNetErrors.getErrorByCode(-170);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNABLE_TO_REUSE_CONNECTION_FOR_PROXY_AUTH');
const err = new Err();

CtConsistencyProofParsingFailedError

Certificate Transparency: Failed to parse the received consistency proof.

  • Name: CtConsistencyProofParsingFailedError
  • Code: -171
  • Description: CT_CONSISTENCY_PROOF_PARSING_FAILED
  • Type: connection
const err = new chromiumNetErrors.CtConsistencyProofParsingFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-171);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CT_CONSISTENCY_PROOF_PARSING_FAILED');
const err = new Err();

SslObsoleteCipherError

The SSL server required an unsupported cipher suite that has since been removed. This error will temporarily be signaled on a fallback for one or two releases immediately following a cipher suite's removal, after which the fallback will be removed.

  • Name: SslObsoleteCipherError
  • Code: -172
  • Description: SSL_OBSOLETE_CIPHER
  • Type: connection
const err = new chromiumNetErrors.SslObsoleteCipherError();
// or
const Err = chromiumNetErrors.getErrorByCode(-172);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_OBSOLETE_CIPHER');
const err = new Err();

WsUpgradeError

When a WebSocket handshake is done successfully and the connection has been upgraded, the URLRequest is cancelled with this error code.

  • Name: WsUpgradeError
  • Code: -173
  • Description: WS_UPGRADE
  • Type: connection
const err = new chromiumNetErrors.WsUpgradeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-173);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('WS_UPGRADE');
const err = new Err();

ReadIfReadyNotImplementedError

Socket ReadIfReady support is not implemented. This error should not be user visible, because the normal Read() method is used as a fallback.

  • Name: ReadIfReadyNotImplementedError
  • Code: -174
  • Description: READ_IF_READY_NOT_IMPLEMENTED
  • Type: connection
const err = new chromiumNetErrors.ReadIfReadyNotImplementedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-174);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('READ_IF_READY_NOT_IMPLEMENTED');
const err = new Err();

NoBufferSpaceError

No socket buffer space is available.

  • Name: NoBufferSpaceError
  • Code: -176
  • Description: NO_BUFFER_SPACE
  • Type: connection
const err = new chromiumNetErrors.NoBufferSpaceError();
// or
const Err = chromiumNetErrors.getErrorByCode(-176);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NO_BUFFER_SPACE');
const err = new Err();

SslClientAuthNoCommonAlgorithmsError

There were no common signature algorithms between our client certificate private key and the server's preferences.

  • Name: SslClientAuthNoCommonAlgorithmsError
  • Code: -177
  • Description: SSL_CLIENT_AUTH_NO_COMMON_ALGORITHMS
  • Type: connection
const err = new chromiumNetErrors.SslClientAuthNoCommonAlgorithmsError();
// or
const Err = chromiumNetErrors.getErrorByCode(-177);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_CLIENT_AUTH_NO_COMMON_ALGORITHMS');
const err = new Err();

EarlyDataRejectedError

TLS 1.3 early data was rejected by the server. This will be received before any data is returned from the socket. The request should be retried with early data disabled.

  • Name: EarlyDataRejectedError
  • Code: -178
  • Description: EARLY_DATA_REJECTED
  • Type: connection
const err = new chromiumNetErrors.EarlyDataRejectedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-178);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('EARLY_DATA_REJECTED');
const err = new Err();

WrongVersionOnEarlyDataError

TLS 1.3 early data was offered, but the server responded with TLS 1.2 or earlier. This is an internal error code to account for a backwards-compatibility issue with early data and TLS 1.2. It will be received before any data is returned from the socket. The request should be retried with early data disabled.

See https://tools.ietf.org/html/rfc8446#appendix-D.3 for details.

  • Name: WrongVersionOnEarlyDataError
  • Code: -179
  • Description: WRONG_VERSION_ON_EARLY_DATA
  • Type: connection
const err = new chromiumNetErrors.WrongVersionOnEarlyDataError();
// or
const Err = chromiumNetErrors.getErrorByCode(-179);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('WRONG_VERSION_ON_EARLY_DATA');
const err = new Err();

Tls13DowngradeDetectedError

TLS 1.3 was enabled, but a lower version was negotiated and the server returned a value indicating it supported TLS 1.3. This is part of a security check in TLS 1.3, but it may also indicate the user is behind a buggy TLS-terminating proxy which implemented TLS 1.2 incorrectly. (See https://crbug.com/boringssl/226.)

  • Name: Tls13DowngradeDetectedError
  • Code: -180
  • Description: TLS13_DOWNGRADE_DETECTED
  • Type: connection
const err = new chromiumNetErrors.Tls13DowngradeDetectedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-180);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TLS13_DOWNGRADE_DETECTED');
const err = new Err();

SslKeyUsageIncompatibleError

The server's certificate has a keyUsage extension incompatible with the negotiated TLS key exchange method.

  • Name: SslKeyUsageIncompatibleError
  • Code: -181
  • Description: SSL_KEY_USAGE_INCOMPATIBLE
  • Type: connection
const err = new chromiumNetErrors.SslKeyUsageIncompatibleError();
// or
const Err = chromiumNetErrors.getErrorByCode(-181);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_KEY_USAGE_INCOMPATIBLE');
const err = new Err();

CertCommonNameInvalidError

The server responded with a certificate whose common name did not match the host name. This could mean:

An attacker has redirected our traffic to their server and is presenting a certificate for which they know the private key.

The server is misconfigured and responding with the wrong cert.

The user is on a wireless network and is being redirected to the network's login page.

The OS has used a DNS search suffix and the server doesn't have a certificate for the abbreviated name in the address bar.

  • Name: CertCommonNameInvalidError
  • Code: -200
  • Description: CERT_COMMON_NAME_INVALID
  • Type: certificate
const err = new chromiumNetErrors.CertCommonNameInvalidError();
// or
const Err = chromiumNetErrors.getErrorByCode(-200);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_COMMON_NAME_INVALID');
const err = new Err();

CertDateInvalidError

The server responded with a certificate that, by our clock, appears to either not yet be valid or to have expired. This could mean:

An attacker is presenting an old certificate for which they have managed to obtain the private key.

The server is misconfigured and is not presenting a valid cert.

Our clock is wrong.

  • Name: CertDateInvalidError
  • Code: -201
  • Description: CERT_DATE_INVALID
  • Type: certificate
const err = new chromiumNetErrors.CertDateInvalidError();
// or
const Err = chromiumNetErrors.getErrorByCode(-201);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_DATE_INVALID');
const err = new Err();

CertAuthorityInvalidError

The server responded with a certificate that is signed by an authority we don't trust. The could mean:

An attacker has substituted the real certificate for a cert that contains their public key and is signed by their cousin.

The server operator has a legitimate certificate from a CA we don't know about, but should trust.

The server is presenting a self-signed certificate, providing no defense against active attackers (but foiling passive attackers).

  • Name: CertAuthorityInvalidError
  • Code: -202
  • Description: CERT_AUTHORITY_INVALID
  • Type: certificate
const err = new chromiumNetErrors.CertAuthorityInvalidError();
// or
const Err = chromiumNetErrors.getErrorByCode(-202);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_AUTHORITY_INVALID');
const err = new Err();

CertContainsErrorsError

The server responded with a certificate that contains errors. This error is not recoverable.

MSDN describes this error as follows: "The SSL certificate contains errors." NOTE: It's unclear how this differs from ERR_CERT_INVALID. For consistency, use that code instead of this one from now on.

  • Name: CertContainsErrorsError
  • Code: -203
  • Description: CERT_CONTAINS_ERRORS
  • Type: certificate
const err = new chromiumNetErrors.CertContainsErrorsError();
// or
const Err = chromiumNetErrors.getErrorByCode(-203);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_CONTAINS_ERRORS');
const err = new Err();

CertNoRevocationMechanismError

The certificate has no mechanism for determining if it is revoked. In effect, this certificate cannot be revoked.

  • Name: CertNoRevocationMechanismError
  • Code: -204
  • Description: CERT_NO_REVOCATION_MECHANISM
  • Type: certificate
const err = new chromiumNetErrors.CertNoRevocationMechanismError();
// or
const Err = chromiumNetErrors.getErrorByCode(-204);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_NO_REVOCATION_MECHANISM');
const err = new Err();

CertUnableToCheckRevocationError

Revocation information for the security certificate for this site is not available. This could mean:

An attacker has compromised the private key in the certificate and is blocking our attempt to find out that the cert was revoked.

The certificate is unrevoked, but the revocation server is busy or unavailable.

  • Name: CertUnableToCheckRevocationError
  • Code: -205
  • Description: CERT_UNABLE_TO_CHECK_REVOCATION
  • Type: certificate
const err = new chromiumNetErrors.CertUnableToCheckRevocationError();
// or
const Err = chromiumNetErrors.getErrorByCode(-205);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_UNABLE_TO_CHECK_REVOCATION');
const err = new Err();

CertRevokedError

The server responded with a certificate has been revoked. We have the capability to ignore this error, but it is probably not the thing to do.

  • Name: CertRevokedError
  • Code: -206
  • Description: CERT_REVOKED
  • Type: certificate
const err = new chromiumNetErrors.CertRevokedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-206);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_REVOKED');
const err = new Err();

CertInvalidError

The server responded with a certificate that is invalid. This error is not recoverable.

MSDN describes this error as follows: "The SSL certificate is invalid."

  • Name: CertInvalidError
  • Code: -207
  • Description: CERT_INVALID
  • Type: certificate
const err = new chromiumNetErrors.CertInvalidError();
// or
const Err = chromiumNetErrors.getErrorByCode(-207);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_INVALID');
const err = new Err();

CertWeakSignatureAlgorithmError

The server responded with a certificate that is signed using a weak signature algorithm.

  • Name: CertWeakSignatureAlgorithmError
  • Code: -208
  • Description: CERT_WEAK_SIGNATURE_ALGORITHM
  • Type: certificate
const err = new chromiumNetErrors.CertWeakSignatureAlgorithmError();
// or
const Err = chromiumNetErrors.getErrorByCode(-208);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_WEAK_SIGNATURE_ALGORITHM');
const err = new Err();

CertNonUniqueNameError

The host name specified in the certificate is not unique.

  • Name: CertNonUniqueNameError
  • Code: -210
  • Description: CERT_NON_UNIQUE_NAME
  • Type: certificate
const err = new chromiumNetErrors.CertNonUniqueNameError();
// or
const Err = chromiumNetErrors.getErrorByCode(-210);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_NON_UNIQUE_NAME');
const err = new Err();

CertWeakKeyError

The server responded with a certificate that contains a weak key (e.g. a too-small RSA key).

  • Name: CertWeakKeyError
  • Code: -211
  • Description: CERT_WEAK_KEY
  • Type: certificate
const err = new chromiumNetErrors.CertWeakKeyError();
// or
const Err = chromiumNetErrors.getErrorByCode(-211);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_WEAK_KEY');
const err = new Err();

CertNameConstraintViolationError

The certificate claimed DNS names that are in violation of name constraints.

  • Name: CertNameConstraintViolationError
  • Code: -212
  • Description: CERT_NAME_CONSTRAINT_VIOLATION
  • Type: certificate
const err = new chromiumNetErrors.CertNameConstraintViolationError();
// or
const Err = chromiumNetErrors.getErrorByCode(-212);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_NAME_CONSTRAINT_VIOLATION');
const err = new Err();

CertValidityTooLongError

The certificate's validity period is too long.

  • Name: CertValidityTooLongError
  • Code: -213
  • Description: CERT_VALIDITY_TOO_LONG
  • Type: certificate
const err = new chromiumNetErrors.CertValidityTooLongError();
// or
const Err = chromiumNetErrors.getErrorByCode(-213);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_VALIDITY_TOO_LONG');
const err = new Err();

CertificateTransparencyRequiredError

Certificate Transparency was required for this connection, but the server did not provide CT information that complied with the policy.

  • Name: CertificateTransparencyRequiredError
  • Code: -214
  • Description: CERTIFICATE_TRANSPARENCY_REQUIRED
  • Type: certificate
const err = new chromiumNetErrors.CertificateTransparencyRequiredError();
// or
const Err = chromiumNetErrors.getErrorByCode(-214);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERTIFICATE_TRANSPARENCY_REQUIRED');
const err = new Err();

CertSymantecLegacyError

The certificate chained to a legacy Symantec root that is no longer trusted. https://g.co/chrome/symantecpkicerts

  • Name: CertSymantecLegacyError
  • Code: -215
  • Description: CERT_SYMANTEC_LEGACY
  • Type: certificate
const err = new chromiumNetErrors.CertSymantecLegacyError();
// or
const Err = chromiumNetErrors.getErrorByCode(-215);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_SYMANTEC_LEGACY');
const err = new Err();

CertKnownInterceptionBlockedError

The certificate is known to be used for interception by an entity other the device owner.

  • Name: CertKnownInterceptionBlockedError
  • Code: -217
  • Description: CERT_KNOWN_INTERCEPTION_BLOCKED
  • Type: certificate
const err = new chromiumNetErrors.CertKnownInterceptionBlockedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-217);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_KNOWN_INTERCEPTION_BLOCKED');
const err = new Err();

SslObsoleteVersionError

The connection uses an obsolete version of SSL/TLS.

  • Name: SslObsoleteVersionError
  • Code: -218
  • Description: SSL_OBSOLETE_VERSION
  • Type: certificate
const err = new chromiumNetErrors.SslObsoleteVersionError();
// or
const Err = chromiumNetErrors.getErrorByCode(-218);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SSL_OBSOLETE_VERSION');
const err = new Err();

CertEndError

The value immediately past the last certificate error code.

  • Name: CertEndError
  • Code: -219
  • Description: CERT_END
  • Type: certificate
const err = new chromiumNetErrors.CertEndError();
// or
const Err = chromiumNetErrors.getErrorByCode(-219);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_END');
const err = new Err();

InvalidUrlError

The URL is invalid.

  • Name: InvalidUrlError
  • Code: -300
  • Description: INVALID_URL
  • Type: http
const err = new chromiumNetErrors.InvalidUrlError();
// or
const Err = chromiumNetErrors.getErrorByCode(-300);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_URL');
const err = new Err();

DisallowedUrlSchemeError

The scheme of the URL is disallowed.

  • Name: DisallowedUrlSchemeError
  • Code: -301
  • Description: DISALLOWED_URL_SCHEME
  • Type: http
const err = new chromiumNetErrors.DisallowedUrlSchemeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-301);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DISALLOWED_URL_SCHEME');
const err = new Err();

UnknownUrlSchemeError

The scheme of the URL is unknown.

  • Name: UnknownUrlSchemeError
  • Code: -302
  • Description: UNKNOWN_URL_SCHEME
  • Type: http
const err = new chromiumNetErrors.UnknownUrlSchemeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-302);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNKNOWN_URL_SCHEME');
const err = new Err();

InvalidRedirectError

Attempting to load an URL resulted in a redirect to an invalid URL.

  • Name: InvalidRedirectError
  • Code: -303
  • Description: INVALID_REDIRECT
  • Type: http
const err = new chromiumNetErrors.InvalidRedirectError();
// or
const Err = chromiumNetErrors.getErrorByCode(-303);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_REDIRECT');
const err = new Err();

TooManyRedirectsError

Attempting to load an URL resulted in too many redirects.

  • Name: TooManyRedirectsError
  • Code: -310
  • Description: TOO_MANY_REDIRECTS
  • Type: http
const err = new chromiumNetErrors.TooManyRedirectsError();
// or
const Err = chromiumNetErrors.getErrorByCode(-310);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TOO_MANY_REDIRECTS');
const err = new Err();

UnsafeRedirectError

Attempting to load an URL resulted in an unsafe redirect (e.g., a redirect to file:// is considered unsafe).

  • Name: UnsafeRedirectError
  • Code: -311
  • Description: UNSAFE_REDIRECT
  • Type: http
const err = new chromiumNetErrors.UnsafeRedirectError();
// or
const Err = chromiumNetErrors.getErrorByCode(-311);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNSAFE_REDIRECT');
const err = new Err();

UnsafePortError

Attempting to load an URL with an unsafe port number. These are port numbers that correspond to services, which are not robust to spurious input that may be constructed as a result of an allowed web construct (e.g., HTTP looks a lot like SMTP, so form submission to port 25 is denied).

  • Name: UnsafePortError
  • Code: -312
  • Description: UNSAFE_PORT
  • Type: http
const err = new chromiumNetErrors.UnsafePortError();
// or
const Err = chromiumNetErrors.getErrorByCode(-312);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNSAFE_PORT');
const err = new Err();

InvalidResponseError

The server's response was invalid.

  • Name: InvalidResponseError
  • Code: -320
  • Description: INVALID_RESPONSE
  • Type: http
const err = new chromiumNetErrors.InvalidResponseError();
// or
const Err = chromiumNetErrors.getErrorByCode(-320);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_RESPONSE');
const err = new Err();

InvalidChunkedEncodingError

Error in chunked transfer encoding.

  • Name: InvalidChunkedEncodingError
  • Code: -321
  • Description: INVALID_CHUNKED_ENCODING
  • Type: http
const err = new chromiumNetErrors.InvalidChunkedEncodingError();
// or
const Err = chromiumNetErrors.getErrorByCode(-321);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_CHUNKED_ENCODING');
const err = new Err();

MethodNotSupportedError

The server did not support the request method.

  • Name: MethodNotSupportedError
  • Code: -322
  • Description: METHOD_NOT_SUPPORTED
  • Type: http
const err = new chromiumNetErrors.MethodNotSupportedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-322);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('METHOD_NOT_SUPPORTED');
const err = new Err();

UnexpectedProxyAuthError

The response was 407 (Proxy Authentication Required), yet we did not send the request to a proxy.

  • Name: UnexpectedProxyAuthError
  • Code: -323
  • Description: UNEXPECTED_PROXY_AUTH
  • Type: http
const err = new chromiumNetErrors.UnexpectedProxyAuthError();
// or
const Err = chromiumNetErrors.getErrorByCode(-323);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNEXPECTED_PROXY_AUTH');
const err = new Err();

EmptyResponseError

The server closed the connection without sending any data.

  • Name: EmptyResponseError
  • Code: -324
  • Description: EMPTY_RESPONSE
  • Type: http
const err = new chromiumNetErrors.EmptyResponseError();
// or
const Err = chromiumNetErrors.getErrorByCode(-324);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('EMPTY_RESPONSE');
const err = new Err();

ResponseHeadersTooBigError

The headers section of the response is too large.

  • Name: ResponseHeadersTooBigError
  • Code: -325
  • Description: RESPONSE_HEADERS_TOO_BIG
  • Type: http
const err = new chromiumNetErrors.ResponseHeadersTooBigError();
// or
const Err = chromiumNetErrors.getErrorByCode(-325);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('RESPONSE_HEADERS_TOO_BIG');
const err = new Err();

PacScriptFailedError

The evaluation of the PAC script failed.

  • Name: PacScriptFailedError
  • Code: -327
  • Description: PAC_SCRIPT_FAILED
  • Type: http
const err = new chromiumNetErrors.PacScriptFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-327);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PAC_SCRIPT_FAILED');
const err = new Err();

RequestRangeNotSatisfiableError

The response was 416 (Requested range not satisfiable) and the server cannot satisfy the range requested.

  • Name: RequestRangeNotSatisfiableError
  • Code: -328
  • Description: REQUEST_RANGE_NOT_SATISFIABLE
  • Type: http
const err = new chromiumNetErrors.RequestRangeNotSatisfiableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-328);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('REQUEST_RANGE_NOT_SATISFIABLE');
const err = new Err();

MalformedIdentityError

The identity used for authentication is invalid.

  • Name: MalformedIdentityError
  • Code: -329
  • Description: MALFORMED_IDENTITY
  • Type: http
const err = new chromiumNetErrors.MalformedIdentityError();
// or
const Err = chromiumNetErrors.getErrorByCode(-329);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('MALFORMED_IDENTITY');
const err = new Err();

ContentDecodingFailedError

Content decoding of the response body failed.

  • Name: ContentDecodingFailedError
  • Code: -330
  • Description: CONTENT_DECODING_FAILED
  • Type: http
const err = new chromiumNetErrors.ContentDecodingFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-330);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONTENT_DECODING_FAILED');
const err = new Err();

NetworkIoSuspendedError

An operation could not be completed because all network IO is suspended.

  • Name: NetworkIoSuspendedError
  • Code: -331
  • Description: NETWORK_IO_SUSPENDED
  • Type: http
const err = new chromiumNetErrors.NetworkIoSuspendedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-331);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NETWORK_IO_SUSPENDED');
const err = new Err();

SynReplyNotReceivedError

FLIP data received without receiving a SYN_REPLY on the stream.

  • Name: SynReplyNotReceivedError
  • Code: -332
  • Description: SYN_REPLY_NOT_RECEIVED
  • Type: http
const err = new chromiumNetErrors.SynReplyNotReceivedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-332);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SYN_REPLY_NOT_RECEIVED');
const err = new Err();

EncodingConversionFailedError

Converting the response to target encoding failed.

  • Name: EncodingConversionFailedError
  • Code: -333
  • Description: ENCODING_CONVERSION_FAILED
  • Type: http
const err = new chromiumNetErrors.EncodingConversionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-333);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ENCODING_CONVERSION_FAILED');
const err = new Err();

UnrecognizedFtpDirectoryListingFormatError

The server sent an FTP directory listing in a format we do not understand.

  • Name: UnrecognizedFtpDirectoryListingFormatError
  • Code: -334
  • Description: UNRECOGNIZED_FTP_DIRECTORY_LISTING_FORMAT
  • Type: http
const err = new chromiumNetErrors.UnrecognizedFtpDirectoryListingFormatError();
// or
const Err = chromiumNetErrors.getErrorByCode(-334);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNRECOGNIZED_FTP_DIRECTORY_LISTING_FORMAT');
const err = new Err();

NoSupportedProxiesError

There are no supported proxies in the provided list.

  • Name: NoSupportedProxiesError
  • Code: -336
  • Description: NO_SUPPORTED_PROXIES
  • Type: http
const err = new chromiumNetErrors.NoSupportedProxiesError();
// or
const Err = chromiumNetErrors.getErrorByCode(-336);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NO_SUPPORTED_PROXIES');
const err = new Err();

Http2ProtocolError

There is an HTTP/2 protocol error.

  • Name: Http2ProtocolError
  • Code: -337
  • Description: HTTP2_PROTOCOL_ERROR
  • Type: http
const err = new chromiumNetErrors.Http2ProtocolError();
// or
const Err = chromiumNetErrors.getErrorByCode(-337);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_PROTOCOL_ERROR');
const err = new Err();

InvalidAuthCredentialsError

Credentials could not be established during HTTP Authentication.

  • Name: InvalidAuthCredentialsError
  • Code: -338
  • Description: INVALID_AUTH_CREDENTIALS
  • Type: http
const err = new chromiumNetErrors.InvalidAuthCredentialsError();
// or
const Err = chromiumNetErrors.getErrorByCode(-338);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_AUTH_CREDENTIALS');
const err = new Err();

UnsupportedAuthSchemeError

An HTTP Authentication scheme was tried which is not supported on this machine.

  • Name: UnsupportedAuthSchemeError
  • Code: -339
  • Description: UNSUPPORTED_AUTH_SCHEME
  • Type: http
const err = new chromiumNetErrors.UnsupportedAuthSchemeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-339);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNSUPPORTED_AUTH_SCHEME');
const err = new Err();

EncodingDetectionFailedError

Detecting the encoding of the response failed.

  • Name: EncodingDetectionFailedError
  • Code: -340
  • Description: ENCODING_DETECTION_FAILED
  • Type: http
const err = new chromiumNetErrors.EncodingDetectionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-340);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ENCODING_DETECTION_FAILED');
const err = new Err();

MissingAuthCredentialsError

(GSSAPI) No Kerberos credentials were available during HTTP Authentication.

  • Name: MissingAuthCredentialsError
  • Code: -341
  • Description: MISSING_AUTH_CREDENTIALS
  • Type: http
const err = new chromiumNetErrors.MissingAuthCredentialsError();
// or
const Err = chromiumNetErrors.getErrorByCode(-341);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('MISSING_AUTH_CREDENTIALS');
const err = new Err();

UnexpectedSecurityLibraryStatusError

An unexpected, but documented, SSPI or GSSAPI status code was returned.

  • Name: UnexpectedSecurityLibraryStatusError
  • Code: -342
  • Description: UNEXPECTED_SECURITY_LIBRARY_STATUS
  • Type: http
const err = new chromiumNetErrors.UnexpectedSecurityLibraryStatusError();
// or
const Err = chromiumNetErrors.getErrorByCode(-342);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNEXPECTED_SECURITY_LIBRARY_STATUS');
const err = new Err();

MisconfiguredAuthEnvironmentError

The environment was not set up correctly for authentication (for example, no KDC could be found or the principal is unknown.

  • Name: MisconfiguredAuthEnvironmentError
  • Code: -343
  • Description: MISCONFIGURED_AUTH_ENVIRONMENT
  • Type: http
const err = new chromiumNetErrors.MisconfiguredAuthEnvironmentError();
// or
const Err = chromiumNetErrors.getErrorByCode(-343);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('MISCONFIGURED_AUTH_ENVIRONMENT');
const err = new Err();

UndocumentedSecurityLibraryStatusError

An undocumented SSPI or GSSAPI status code was returned.

  • Name: UndocumentedSecurityLibraryStatusError
  • Code: -344
  • Description: UNDOCUMENTED_SECURITY_LIBRARY_STATUS
  • Type: http
const err = new chromiumNetErrors.UndocumentedSecurityLibraryStatusError();
// or
const Err = chromiumNetErrors.getErrorByCode(-344);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('UNDOCUMENTED_SECURITY_LIBRARY_STATUS');
const err = new Err();

ResponseBodyTooBigToDrainError

The HTTP response was too big to drain.

  • Name: ResponseBodyTooBigToDrainError
  • Code: -345
  • Description: RESPONSE_BODY_TOO_BIG_TO_DRAIN
  • Type: http
const err = new chromiumNetErrors.ResponseBodyTooBigToDrainError();
// or
const Err = chromiumNetErrors.getErrorByCode(-345);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('RESPONSE_BODY_TOO_BIG_TO_DRAIN');
const err = new Err();

ResponseHeadersMultipleContentLengthError

The HTTP response contained multiple distinct Content-Length headers.

  • Name: ResponseHeadersMultipleContentLengthError
  • Code: -346
  • Description: RESPONSE_HEADERS_MULTIPLE_CONTENT_LENGTH
  • Type: http
const err = new chromiumNetErrors.ResponseHeadersMultipleContentLengthError();
// or
const Err = chromiumNetErrors.getErrorByCode(-346);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('RESPONSE_HEADERS_MULTIPLE_CONTENT_LENGTH');
const err = new Err();

IncompleteHttp2HeadersError

HTTP/2 headers have been received, but not all of them - status or version headers are missing, so we're expecting additional frames to complete them.

  • Name: IncompleteHttp2HeadersError
  • Code: -347
  • Description: INCOMPLETE_HTTP2_HEADERS
  • Type: http
const err = new chromiumNetErrors.IncompleteHttp2HeadersError();
// or
const Err = chromiumNetErrors.getErrorByCode(-347);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INCOMPLETE_HTTP2_HEADERS');
const err = new Err();

PacNotInDhcpError

No PAC URL configuration could be retrieved from DHCP. This can indicate either a failure to retrieve the DHCP configuration, or that there was no PAC URL configured in DHCP.

  • Name: PacNotInDhcpError
  • Code: -348
  • Description: PAC_NOT_IN_DHCP
  • Type: http
const err = new chromiumNetErrors.PacNotInDhcpError();
// or
const Err = chromiumNetErrors.getErrorByCode(-348);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PAC_NOT_IN_DHCP');
const err = new Err();

ResponseHeadersMultipleContentDispositionError

The HTTP response contained multiple Content-Disposition headers.

  • Name: ResponseHeadersMultipleContentDispositionError
  • Code: -349
  • Description: RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION
  • Type: http
const err = new chromiumNetErrors.ResponseHeadersMultipleContentDispositionError();
// or
const Err = chromiumNetErrors.getErrorByCode(-349);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION');
const err = new Err();

ResponseHeadersMultipleLocationError

The HTTP response contained multiple Location headers.

  • Name: ResponseHeadersMultipleLocationError
  • Code: -350
  • Description: RESPONSE_HEADERS_MULTIPLE_LOCATION
  • Type: http
const err = new chromiumNetErrors.ResponseHeadersMultipleLocationError();
// or
const Err = chromiumNetErrors.getErrorByCode(-350);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('RESPONSE_HEADERS_MULTIPLE_LOCATION');
const err = new Err();

Http2ServerRefusedStreamError

HTTP/2 server refused the request without processing, and sent either a GOAWAY frame with error code NO_ERROR and Last-Stream-ID lower than the stream id corresponding to the request indicating that this request has not been processed yet, or a RST_STREAM frame with error code REFUSED_STREAM. Client MAY retry (on a different connection). See RFC7540 Section 8.1.4.

  • Name: Http2ServerRefusedStreamError
  • Code: -351
  • Description: HTTP2_SERVER_REFUSED_STREAM
  • Type: http
const err = new chromiumNetErrors.Http2ServerRefusedStreamError();
// or
const Err = chromiumNetErrors.getErrorByCode(-351);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_SERVER_REFUSED_STREAM');
const err = new Err();

Http2PingFailedError

HTTP/2 server didn't respond to the PING message.

  • Name: Http2PingFailedError
  • Code: -352
  • Description: HTTP2_PING_FAILED
  • Type: http
const err = new chromiumNetErrors.Http2PingFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-352);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_PING_FAILED');
const err = new Err();

ContentLengthMismatchError

The HTTP response body transferred fewer bytes than were advertised by the Content-Length header when the connection is closed.

  • Name: ContentLengthMismatchError
  • Code: -354
  • Description: CONTENT_LENGTH_MISMATCH
  • Type: http
const err = new chromiumNetErrors.ContentLengthMismatchError();
// or
const Err = chromiumNetErrors.getErrorByCode(-354);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONTENT_LENGTH_MISMATCH');
const err = new Err();

IncompleteChunkedEncodingError

The HTTP response body is transferred with Chunked-Encoding, but the terminating zero-length chunk was never sent when the connection is closed.

  • Name: IncompleteChunkedEncodingError
  • Code: -355
  • Description: INCOMPLETE_CHUNKED_ENCODING
  • Type: http
const err = new chromiumNetErrors.IncompleteChunkedEncodingError();
// or
const Err = chromiumNetErrors.getErrorByCode(-355);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INCOMPLETE_CHUNKED_ENCODING');
const err = new Err();

QuicProtocolError

There is a QUIC protocol error.

  • Name: QuicProtocolError
  • Code: -356
  • Description: QUIC_PROTOCOL_ERROR
  • Type: http
const err = new chromiumNetErrors.QuicProtocolError();
// or
const Err = chromiumNetErrors.getErrorByCode(-356);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('QUIC_PROTOCOL_ERROR');
const err = new Err();

ResponseHeadersTruncatedError

The HTTP headers were truncated by an EOF.

  • Name: ResponseHeadersTruncatedError
  • Code: -357
  • Description: RESPONSE_HEADERS_TRUNCATED
  • Type: http
const err = new chromiumNetErrors.ResponseHeadersTruncatedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-357);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('RESPONSE_HEADERS_TRUNCATED');
const err = new Err();

QuicHandshakeFailedError

The QUIC crytpo handshake failed. This means that the server was unable to read any requests sent, so they may be resent.

  • Name: QuicHandshakeFailedError
  • Code: -358
  • Description: QUIC_HANDSHAKE_FAILED
  • Type: http
const err = new chromiumNetErrors.QuicHandshakeFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-358);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('QUIC_HANDSHAKE_FAILED');
const err = new Err();

Http2InadequateTransportSecurityError

Transport security is inadequate for the HTTP/2 version.

  • Name: Http2InadequateTransportSecurityError
  • Code: -360
  • Description: HTTP2_INADEQUATE_TRANSPORT_SECURITY
  • Type: http
const err = new chromiumNetErrors.Http2InadequateTransportSecurityError();
// or
const Err = chromiumNetErrors.getErrorByCode(-360);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_INADEQUATE_TRANSPORT_SECURITY');
const err = new Err();

Http2FlowControlError

The peer violated HTTP/2 flow control.

  • Name: Http2FlowControlError
  • Code: -361
  • Description: HTTP2_FLOW_CONTROL_ERROR
  • Type: http
const err = new chromiumNetErrors.Http2FlowControlError();
// or
const Err = chromiumNetErrors.getErrorByCode(-361);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_FLOW_CONTROL_ERROR');
const err = new Err();

Http2FrameSizeError

The peer sent an improperly sized HTTP/2 frame.

  • Name: Http2FrameSizeError
  • Code: -362
  • Description: HTTP2_FRAME_SIZE_ERROR
  • Type: http
const err = new chromiumNetErrors.Http2FrameSizeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-362);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_FRAME_SIZE_ERROR');
const err = new Err();

Http2CompressionError

Decoding or encoding of compressed HTTP/2 headers failed.

  • Name: Http2CompressionError
  • Code: -363
  • Description: HTTP2_COMPRESSION_ERROR
  • Type: http
const err = new chromiumNetErrors.Http2CompressionError();
// or
const Err = chromiumNetErrors.getErrorByCode(-363);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_COMPRESSION_ERROR');
const err = new Err();

ProxyAuthRequestedWithNoConnectionError

Proxy Auth Requested without a valid Client Socket Handle.

  • Name: ProxyAuthRequestedWithNoConnectionError
  • Code: -364
  • Description: PROXY_AUTH_REQUESTED_WITH_NO_CONNECTION
  • Type: http
const err = new chromiumNetErrors.ProxyAuthRequestedWithNoConnectionError();
// or
const Err = chromiumNetErrors.getErrorByCode(-364);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PROXY_AUTH_REQUESTED_WITH_NO_CONNECTION');
const err = new Err();

Http_1_1RequiredError

HTTP_1_1_REQUIRED error code received on HTTP/2 session.

  • Name: Http_1_1RequiredError
  • Code: -365
  • Description: HTTP_1_1_REQUIRED
  • Type: http
const err = new chromiumNetErrors.Http_1_1RequiredError();
// or
const Err = chromiumNetErrors.getErrorByCode(-365);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP_1_1_REQUIRED');
const err = new Err();

ProxyHttp_1_1RequiredError

HTTP_1_1_REQUIRED error code received on HTTP/2 session to proxy.

  • Name: ProxyHttp_1_1RequiredError
  • Code: -366
  • Description: PROXY_HTTP_1_1_REQUIRED
  • Type: http
const err = new chromiumNetErrors.ProxyHttp_1_1RequiredError();
// or
const Err = chromiumNetErrors.getErrorByCode(-366);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PROXY_HTTP_1_1_REQUIRED');
const err = new Err();

PacScriptTerminatedError

The PAC script terminated fatally and must be reloaded.

  • Name: PacScriptTerminatedError
  • Code: -367
  • Description: PAC_SCRIPT_TERMINATED
  • Type: http
const err = new chromiumNetErrors.PacScriptTerminatedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-367);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PAC_SCRIPT_TERMINATED');
const err = new Err();

InvalidHttpResponseError

The server was expected to return an HTTP/1.x response, but did not. Rather than treat it as HTTP/0.9, this error is returned.

  • Name: InvalidHttpResponseError
  • Code: -370
  • Description: INVALID_HTTP_RESPONSE
  • Type: http
const err = new chromiumNetErrors.InvalidHttpResponseError();
// or
const Err = chromiumNetErrors.getErrorByCode(-370);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_HTTP_RESPONSE');
const err = new Err();

ContentDecodingInitFailedError

Initializing content decoding failed.

  • Name: ContentDecodingInitFailedError
  • Code: -371
  • Description: CONTENT_DECODING_INIT_FAILED
  • Type: http
const err = new chromiumNetErrors.ContentDecodingInitFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-371);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CONTENT_DECODING_INIT_FAILED');
const err = new Err();

Http2RstStreamNoErrorReceivedError

Received HTTP/2 RST_STREAM frame with NO_ERROR error code. This error should be handled internally by HTTP/2 code, and should not make it above the SpdyStream layer.

  • Name: Http2RstStreamNoErrorReceivedError
  • Code: -372
  • Description: HTTP2_RST_STREAM_NO_ERROR_RECEIVED
  • Type: http
const err = new chromiumNetErrors.Http2RstStreamNoErrorReceivedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-372);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_RST_STREAM_NO_ERROR_RECEIVED');
const err = new Err();

Http2PushedStreamNotAvailableError

The pushed stream claimed by the request is no longer available.

  • Name: Http2PushedStreamNotAvailableError
  • Code: -373
  • Description: HTTP2_PUSHED_STREAM_NOT_AVAILABLE
  • Type: http
const err = new chromiumNetErrors.Http2PushedStreamNotAvailableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-373);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_PUSHED_STREAM_NOT_AVAILABLE');
const err = new Err();

Http2ClaimedPushedStreamResetByServerError

A pushed stream was claimed and later reset by the server. When this happens, the request should be retried.

  • Name: Http2ClaimedPushedStreamResetByServerError
  • Code: -374
  • Description: HTTP2_CLAIMED_PUSHED_STREAM_RESET_BY_SERVER
  • Type: http
const err = new chromiumNetErrors.Http2ClaimedPushedStreamResetByServerError();
// or
const Err = chromiumNetErrors.getErrorByCode(-374);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_CLAIMED_PUSHED_STREAM_RESET_BY_SERVER');
const err = new Err();

TooManyRetriesError

An HTTP transaction was retried too many times due for authentication or invalid certificates. This may be due to a bug in the net stack that would otherwise infinite loop, or if the server or proxy continually requests fresh credentials or presents a fresh invalid certificate.

  • Name: TooManyRetriesError
  • Code: -375
  • Description: TOO_MANY_RETRIES
  • Type: http
const err = new chromiumNetErrors.TooManyRetriesError();
// or
const Err = chromiumNetErrors.getErrorByCode(-375);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TOO_MANY_RETRIES');
const err = new Err();

Http2StreamClosedError

Received an HTTP/2 frame on a closed stream.

  • Name: Http2StreamClosedError
  • Code: -376
  • Description: HTTP2_STREAM_CLOSED
  • Type: http
const err = new chromiumNetErrors.Http2StreamClosedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-376);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_STREAM_CLOSED');
const err = new Err();

Http2ClientRefusedStreamError

Client is refusing an HTTP/2 stream.

  • Name: Http2ClientRefusedStreamError
  • Code: -377
  • Description: HTTP2_CLIENT_REFUSED_STREAM
  • Type: http
const err = new chromiumNetErrors.Http2ClientRefusedStreamError();
// or
const Err = chromiumNetErrors.getErrorByCode(-377);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_CLIENT_REFUSED_STREAM');
const err = new Err();

Http2PushedResponseDoesNotMatchError

A pushed HTTP/2 stream was claimed by a request based on matching URL and request headers, but the pushed response headers do not match the request.

  • Name: Http2PushedResponseDoesNotMatchError
  • Code: -378
  • Description: HTTP2_PUSHED_RESPONSE_DOES_NOT_MATCH
  • Type: http
const err = new chromiumNetErrors.Http2PushedResponseDoesNotMatchError();
// or
const Err = chromiumNetErrors.getErrorByCode(-378);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP2_PUSHED_RESPONSE_DOES_NOT_MATCH');
const err = new Err();

HttpResponseCodeFailureError

The server returned a non-2xx HTTP response code.

Not that this error is only used by certain APIs that interpret the HTTP response itself. URLRequest for instance just passes most non-2xx response back as success.

  • Name: HttpResponseCodeFailureError
  • Code: -379
  • Description: HTTP_RESPONSE_CODE_FAILURE
  • Type: http
const err = new chromiumNetErrors.HttpResponseCodeFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-379);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('HTTP_RESPONSE_CODE_FAILURE');
const err = new Err();

QuicCertRootNotKnownError

The certificate presented on a QUIC connection does not chain to a known root and the origin connected to is not on a list of domains where unknown roots are allowed.

  • Name: QuicCertRootNotKnownError
  • Code: -380
  • Description: QUIC_CERT_ROOT_NOT_KNOWN
  • Type: http
const err = new chromiumNetErrors.QuicCertRootNotKnownError();
// or
const Err = chromiumNetErrors.getErrorByCode(-380);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('QUIC_CERT_ROOT_NOT_KNOWN');
const err = new Err();

QuicGoawayRequestCanBeRetriedError

A GOAWAY frame has been received indicating that the request has not been processed and is therefore safe to retry on a different connection.

  • Name: QuicGoawayRequestCanBeRetriedError
  • Code: -381
  • Description: QUIC_GOAWAY_REQUEST_CAN_BE_RETRIED
  • Type: http
const err = new chromiumNetErrors.QuicGoawayRequestCanBeRetriedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-381);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('QUIC_GOAWAY_REQUEST_CAN_BE_RETRIED');
const err = new Err();

CacheMissError

The cache does not have the requested entry.

  • Name: CacheMissError
  • Code: -400
  • Description: CACHE_MISS
  • Type: cache
const err = new chromiumNetErrors.CacheMissError();
// or
const Err = chromiumNetErrors.getErrorByCode(-400);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_MISS');
const err = new Err();

CacheReadFailureError

Unable to read from the disk cache.

  • Name: CacheReadFailureError
  • Code: -401
  • Description: CACHE_READ_FAILURE
  • Type: cache
const err = new chromiumNetErrors.CacheReadFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-401);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_READ_FAILURE');
const err = new Err();

CacheWriteFailureError

Unable to write to the disk cache.

  • Name: CacheWriteFailureError
  • Code: -402
  • Description: CACHE_WRITE_FAILURE
  • Type: cache
const err = new chromiumNetErrors.CacheWriteFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-402);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_WRITE_FAILURE');
const err = new Err();

CacheOperationNotSupportedError

The operation is not supported for this entry.

  • Name: CacheOperationNotSupportedError
  • Code: -403
  • Description: CACHE_OPERATION_NOT_SUPPORTED
  • Type: cache
const err = new chromiumNetErrors.CacheOperationNotSupportedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-403);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_OPERATION_NOT_SUPPORTED');
const err = new Err();

CacheOpenFailureError

The disk cache is unable to open this entry.

  • Name: CacheOpenFailureError
  • Code: -404
  • Description: CACHE_OPEN_FAILURE
  • Type: cache
const err = new chromiumNetErrors.CacheOpenFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-404);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_OPEN_FAILURE');
const err = new Err();

CacheCreateFailureError

The disk cache is unable to create this entry.

  • Name: CacheCreateFailureError
  • Code: -405
  • Description: CACHE_CREATE_FAILURE
  • Type: cache
const err = new chromiumNetErrors.CacheCreateFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-405);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_CREATE_FAILURE');
const err = new Err();

CacheRaceError

Multiple transactions are racing to create disk cache entries. This is an internal error returned from the HttpCache to the HttpCacheTransaction that tells the transaction to restart the entry-creation logic because the state of the cache has changed.

  • Name: CacheRaceError
  • Code: -406
  • Description: CACHE_RACE
  • Type: cache
const err = new chromiumNetErrors.CacheRaceError();
// or
const Err = chromiumNetErrors.getErrorByCode(-406);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_RACE');
const err = new Err();

CacheChecksumReadFailureError

The cache was unable to read a checksum record on an entry. This can be returned from attempts to read from the cache. It is an internal error, returned by the SimpleCache backend, but not by any URLRequest methods or members.

  • Name: CacheChecksumReadFailureError
  • Code: -407
  • Description: CACHE_CHECKSUM_READ_FAILURE
  • Type: cache
const err = new chromiumNetErrors.CacheChecksumReadFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-407);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_CHECKSUM_READ_FAILURE');
const err = new Err();

CacheChecksumMismatchError

The cache found an entry with an invalid checksum. This can be returned from attempts to read from the cache. It is an internal error, returned by the SimpleCache backend, but not by any URLRequest methods or members.

  • Name: CacheChecksumMismatchError
  • Code: -408
  • Description: CACHE_CHECKSUM_MISMATCH
  • Type: cache
const err = new chromiumNetErrors.CacheChecksumMismatchError();
// or
const Err = chromiumNetErrors.getErrorByCode(-408);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_CHECKSUM_MISMATCH');
const err = new Err();

CacheLockTimeoutError

Internal error code for the HTTP cache. The cache lock timeout has fired.

  • Name: CacheLockTimeoutError
  • Code: -409
  • Description: CACHE_LOCK_TIMEOUT
  • Type: cache
const err = new chromiumNetErrors.CacheLockTimeoutError();
// or
const Err = chromiumNetErrors.getErrorByCode(-409);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_LOCK_TIMEOUT');
const err = new Err();

CacheAuthFailureAfterReadError

Received a challenge after the transaction has read some data, and the credentials aren't available. There isn't a way to get them at that point.

  • Name: CacheAuthFailureAfterReadError
  • Code: -410
  • Description: CACHE_AUTH_FAILURE_AFTER_READ
  • Type: cache
const err = new chromiumNetErrors.CacheAuthFailureAfterReadError();
// or
const Err = chromiumNetErrors.getErrorByCode(-410);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_AUTH_FAILURE_AFTER_READ');
const err = new Err();

CacheEntryNotSuitableError

Internal not-quite error code for the HTTP cache. In-memory hints suggest that the cache entry would not have been useable with the transaction's current configuration (e.g. load flags, mode, etc.)

  • Name: CacheEntryNotSuitableError
  • Code: -411
  • Description: CACHE_ENTRY_NOT_SUITABLE
  • Type: cache
const err = new chromiumNetErrors.CacheEntryNotSuitableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-411);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_ENTRY_NOT_SUITABLE');
const err = new Err();

CacheDoomFailureError

The disk cache is unable to doom this entry.

  • Name: CacheDoomFailureError
  • Code: -412
  • Description: CACHE_DOOM_FAILURE
  • Type: cache
const err = new chromiumNetErrors.CacheDoomFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-412);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_DOOM_FAILURE');
const err = new Err();

CacheOpenOrCreateFailureError

The disk cache is unable to open or create this entry.

  • Name: CacheOpenOrCreateFailureError
  • Code: -413
  • Description: CACHE_OPEN_OR_CREATE_FAILURE
  • Type: cache
const err = new chromiumNetErrors.CacheOpenOrCreateFailureError();
// or
const Err = chromiumNetErrors.getErrorByCode(-413);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CACHE_OPEN_OR_CREATE_FAILURE');
const err = new Err();

InsecureResponseError

The server's response was insecure (e.g. there was a cert error).

  • Name: InsecureResponseError
  • Code: -501
  • Description: INSECURE_RESPONSE
  • Type: unknown
const err = new chromiumNetErrors.InsecureResponseError();
// or
const Err = chromiumNetErrors.getErrorByCode(-501);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INSECURE_RESPONSE');
const err = new Err();

NoPrivateKeyForCertError

An attempt to import a client certificate failed, as the user's key database lacked a corresponding private key.

  • Name: NoPrivateKeyForCertError
  • Code: -502
  • Description: NO_PRIVATE_KEY_FOR_CERT
  • Type: unknown
const err = new chromiumNetErrors.NoPrivateKeyForCertError();
// or
const Err = chromiumNetErrors.getErrorByCode(-502);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('NO_PRIVATE_KEY_FOR_CERT');
const err = new Err();

AddUserCertFailedError

An error adding a certificate to the OS certificate database.

  • Name: AddUserCertFailedError
  • Code: -503
  • Description: ADD_USER_CERT_FAILED
  • Type: unknown
const err = new chromiumNetErrors.AddUserCertFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-503);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('ADD_USER_CERT_FAILED');
const err = new Err();

InvalidSignedExchangeError

An error occurred while handling a signed exchange.

  • Name: InvalidSignedExchangeError
  • Code: -504
  • Description: INVALID_SIGNED_EXCHANGE
  • Type: unknown
const err = new chromiumNetErrors.InvalidSignedExchangeError();
// or
const Err = chromiumNetErrors.getErrorByCode(-504);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_SIGNED_EXCHANGE');
const err = new Err();

InvalidWebBundleError

An error occurred while handling a Web Bundle source.

  • Name: InvalidWebBundleError
  • Code: -505
  • Description: INVALID_WEB_BUNDLE
  • Type: unknown
const err = new chromiumNetErrors.InvalidWebBundleError();
// or
const Err = chromiumNetErrors.getErrorByCode(-505);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('INVALID_WEB_BUNDLE');
const err = new Err();

TrustTokenOperationFailedError

A Trust Tokens protocol operation-executing request failed for one of a number of reasons (precondition failure, internal error, bad response).

  • Name: TrustTokenOperationFailedError
  • Code: -506
  • Description: TRUST_TOKEN_OPERATION_FAILED
  • Type: unknown
const err = new chromiumNetErrors.TrustTokenOperationFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-506);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TRUST_TOKEN_OPERATION_FAILED');
const err = new Err();

TrustTokenOperationSuccessWithoutSendingRequestError

When handling a Trust Tokens protocol operation-executing request, the system was able to execute the request's Trust Tokens operation without sending the request to its destination: for instance, the results could have been present in a local cache (for redemption) or the operation could have been diverted to a local provider (for "platform-provided" issuance).

  • Name: TrustTokenOperationSuccessWithoutSendingRequestError
  • Code: -507
  • Description: TRUST_TOKEN_OPERATION_SUCCESS_WITHOUT_SENDING_REQUEST
  • Type: unknown
const err = new chromiumNetErrors.TrustTokenOperationSuccessWithoutSendingRequestError();
// or
const Err = chromiumNetErrors.getErrorByCode(-507);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('TRUST_TOKEN_OPERATION_SUCCESS_WITHOUT_SENDING_REQUEST');
const err = new Err();

FtpFailedError

A generic error for failed FTP control connection command. If possible, please use or add a more specific error code.

  • Name: FtpFailedError
  • Code: -601
  • Description: FTP_FAILED
  • Type: ftp
const err = new chromiumNetErrors.FtpFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-601);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FTP_FAILED');
const err = new Err();

FtpServiceUnavailableError

The server cannot fulfill the request at this point. This is a temporary error. FTP response code 421.

  • Name: FtpServiceUnavailableError
  • Code: -602
  • Description: FTP_SERVICE_UNAVAILABLE
  • Type: ftp
const err = new chromiumNetErrors.FtpServiceUnavailableError();
// or
const Err = chromiumNetErrors.getErrorByCode(-602);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FTP_SERVICE_UNAVAILABLE');
const err = new Err();

FtpTransferAbortedError

The server has aborted the transfer. FTP response code 426.

  • Name: FtpTransferAbortedError
  • Code: -603
  • Description: FTP_TRANSFER_ABORTED
  • Type: ftp
const err = new chromiumNetErrors.FtpTransferAbortedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-603);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FTP_TRANSFER_ABORTED');
const err = new Err();

FtpFileBusyError

The file is busy, or some other temporary error condition on opening the file. FTP response code 450.

  • Name: FtpFileBusyError
  • Code: -604
  • Description: FTP_FILE_BUSY
  • Type: ftp
const err = new chromiumNetErrors.FtpFileBusyError();
// or
const Err = chromiumNetErrors.getErrorByCode(-604);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FTP_FILE_BUSY');
const err = new Err();

FtpSyntaxError

Server rejected our command because of syntax errors. FTP response codes 500, 501.

  • Name: FtpSyntaxError
  • Code: -605
  • Description: FTP_SYNTAX_ERROR
  • Type: ftp
const err = new chromiumNetErrors.FtpSyntaxError();
// or
const Err = chromiumNetErrors.getErrorByCode(-605);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FTP_SYNTAX_ERROR');
const err = new Err();

FtpCommandNotSupportedError

Server does not support the command we issued. FTP response codes 502, 504.

  • Name: FtpCommandNotSupportedError
  • Code: -606
  • Description: FTP_COMMAND_NOT_SUPPORTED
  • Type: ftp
const err = new chromiumNetErrors.FtpCommandNotSupportedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-606);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FTP_COMMAND_NOT_SUPPORTED');
const err = new Err();

FtpBadCommandSequenceError

Server rejected our command because we didn't issue the commands in right order. FTP response code 503.

  • Name: FtpBadCommandSequenceError
  • Code: -607
  • Description: FTP_BAD_COMMAND_SEQUENCE
  • Type: ftp
const err = new chromiumNetErrors.FtpBadCommandSequenceError();
// or
const Err = chromiumNetErrors.getErrorByCode(-607);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('FTP_BAD_COMMAND_SEQUENCE');
const err = new Err();

Pkcs12ImportBadPasswordError

PKCS #12 import failed due to incorrect password.

  • Name: Pkcs12ImportBadPasswordError
  • Code: -701
  • Description: PKCS12_IMPORT_BAD_PASSWORD
  • Type: certificate-manager
const err = new chromiumNetErrors.Pkcs12ImportBadPasswordError();
// or
const Err = chromiumNetErrors.getErrorByCode(-701);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PKCS12_IMPORT_BAD_PASSWORD');
const err = new Err();

Pkcs12ImportFailedError

PKCS #12 import failed due to other error.

  • Name: Pkcs12ImportFailedError
  • Code: -702
  • Description: PKCS12_IMPORT_FAILED
  • Type: certificate-manager
const err = new chromiumNetErrors.Pkcs12ImportFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-702);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PKCS12_IMPORT_FAILED');
const err = new Err();

ImportCaCertNotCaError

CA import failed - not a CA cert.

  • Name: ImportCaCertNotCaError
  • Code: -703
  • Description: IMPORT_CA_CERT_NOT_CA
  • Type: certificate-manager
const err = new chromiumNetErrors.ImportCaCertNotCaError();
// or
const Err = chromiumNetErrors.getErrorByCode(-703);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('IMPORT_CA_CERT_NOT_CA');
const err = new Err();

ImportCertAlreadyExistsError

Import failed - certificate already exists in database. Note it's a little weird this is an error but reimporting a PKCS12 is ok (no-op). That's how Mozilla does it, though.

  • Name: ImportCertAlreadyExistsError
  • Code: -704
  • Description: IMPORT_CERT_ALREADY_EXISTS
  • Type: certificate-manager
const err = new chromiumNetErrors.ImportCertAlreadyExistsError();
// or
const Err = chromiumNetErrors.getErrorByCode(-704);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('IMPORT_CERT_ALREADY_EXISTS');
const err = new Err();

ImportCaCertFailedError

CA import failed due to some other error.

  • Name: ImportCaCertFailedError
  • Code: -705
  • Description: IMPORT_CA_CERT_FAILED
  • Type: certificate-manager
const err = new chromiumNetErrors.ImportCaCertFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-705);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('IMPORT_CA_CERT_FAILED');
const err = new Err();

ImportServerCertFailedError

Server certificate import failed due to some internal error.

  • Name: ImportServerCertFailedError
  • Code: -706
  • Description: IMPORT_SERVER_CERT_FAILED
  • Type: certificate-manager
const err = new chromiumNetErrors.ImportServerCertFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-706);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('IMPORT_SERVER_CERT_FAILED');
const err = new Err();

Pkcs12ImportInvalidMacError

PKCS #12 import failed due to invalid MAC.

  • Name: Pkcs12ImportInvalidMacError
  • Code: -707
  • Description: PKCS12_IMPORT_INVALID_MAC
  • Type: certificate-manager
const err = new chromiumNetErrors.Pkcs12ImportInvalidMacError();
// or
const Err = chromiumNetErrors.getErrorByCode(-707);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PKCS12_IMPORT_INVALID_MAC');
const err = new Err();

Pkcs12ImportInvalidFileError

PKCS #12 import failed due to invalid/corrupt file.

  • Name: Pkcs12ImportInvalidFileError
  • Code: -708
  • Description: PKCS12_IMPORT_INVALID_FILE
  • Type: certificate-manager
const err = new chromiumNetErrors.Pkcs12ImportInvalidFileError();
// or
const Err = chromiumNetErrors.getErrorByCode(-708);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PKCS12_IMPORT_INVALID_FILE');
const err = new Err();

Pkcs12ImportUnsupportedError

PKCS #12 import failed due to unsupported features.

  • Name: Pkcs12ImportUnsupportedError
  • Code: -709
  • Description: PKCS12_IMPORT_UNSUPPORTED
  • Type: certificate-manager
const err = new chromiumNetErrors.Pkcs12ImportUnsupportedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-709);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PKCS12_IMPORT_UNSUPPORTED');
const err = new Err();

KeyGenerationFailedError

Key generation failed.

  • Name: KeyGenerationFailedError
  • Code: -710
  • Description: KEY_GENERATION_FAILED
  • Type: certificate-manager
const err = new chromiumNetErrors.KeyGenerationFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-710);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('KEY_GENERATION_FAILED');
const err = new Err();

PrivateKeyExportFailedError

Failure to export private key.

  • Name: PrivateKeyExportFailedError
  • Code: -712
  • Description: PRIVATE_KEY_EXPORT_FAILED
  • Type: certificate-manager
const err = new chromiumNetErrors.PrivateKeyExportFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-712);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('PRIVATE_KEY_EXPORT_FAILED');
const err = new Err();

SelfSignedCertGenerationFailedError

Self-signed certificate generation failed.

  • Name: SelfSignedCertGenerationFailedError
  • Code: -713
  • Description: SELF_SIGNED_CERT_GENERATION_FAILED
  • Type: certificate-manager
const err = new chromiumNetErrors.SelfSignedCertGenerationFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-713);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('SELF_SIGNED_CERT_GENERATION_FAILED');
const err = new Err();

CertDatabaseChangedError

The certificate database changed in some way.

  • Name: CertDatabaseChangedError
  • Code: -714
  • Description: CERT_DATABASE_CHANGED
  • Type: certificate-manager
const err = new chromiumNetErrors.CertDatabaseChangedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-714);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('CERT_DATABASE_CHANGED');
const err = new Err();

DnsMalformedResponseError

DNS resolver received a malformed response.

  • Name: DnsMalformedResponseError
  • Code: -800
  • Description: DNS_MALFORMED_RESPONSE
  • Type: dns
const err = new chromiumNetErrors.DnsMalformedResponseError();
// or
const Err = chromiumNetErrors.getErrorByCode(-800);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_MALFORMED_RESPONSE');
const err = new Err();

DnsServerRequiresTcpError

DNS server requires TCP

  • Name: DnsServerRequiresTcpError
  • Code: -801
  • Description: DNS_SERVER_REQUIRES_TCP
  • Type: dns
const err = new chromiumNetErrors.DnsServerRequiresTcpError();
// or
const Err = chromiumNetErrors.getErrorByCode(-801);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_SERVER_REQUIRES_TCP');
const err = new Err();

DnsServerFailedError

DNS server failed. This error is returned for all of the following error conditions: 1 - Format error - The name server was unable to interpret the query. 2 - Server failure - The name server was unable to process this query due to a problem with the name server. 4 - Not Implemented - The name server does not support the requested kind of query. 5 - Refused - The name server refuses to perform the specified operation for policy reasons.

  • Name: DnsServerFailedError
  • Code: -802
  • Description: DNS_SERVER_FAILED
  • Type: dns
const err = new chromiumNetErrors.DnsServerFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-802);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_SERVER_FAILED');
const err = new Err();

DnsTimedOutError

DNS transaction timed out.

  • Name: DnsTimedOutError
  • Code: -803
  • Description: DNS_TIMED_OUT
  • Type: dns
const err = new chromiumNetErrors.DnsTimedOutError();
// or
const Err = chromiumNetErrors.getErrorByCode(-803);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_TIMED_OUT');
const err = new Err();

DnsCacheMissError

The entry was not found in cache or other local sources, for lookups where only local sources were queried. TODO(ericorth): Consider renaming to DNS_LOCAL_MISS or something like that as the cache is not necessarily queried either.

  • Name: DnsCacheMissError
  • Code: -804
  • Description: DNS_CACHE_MISS
  • Type: dns
const err = new chromiumNetErrors.DnsCacheMissError();
// or
const Err = chromiumNetErrors.getErrorByCode(-804);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_CACHE_MISS');
const err = new Err();

DnsSearchEmptyError

Suffix search list rules prevent resolution of the given host name.

  • Name: DnsSearchEmptyError
  • Code: -805
  • Description: DNS_SEARCH_EMPTY
  • Type: dns
const err = new chromiumNetErrors.DnsSearchEmptyError();
// or
const Err = chromiumNetErrors.getErrorByCode(-805);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_SEARCH_EMPTY');
const err = new Err();

DnsSortError

Failed to sort addresses according to RFC3484.

  • Name: DnsSortError
  • Code: -806
  • Description: DNS_SORT_ERROR
  • Type: dns
const err = new chromiumNetErrors.DnsSortError();
// or
const Err = chromiumNetErrors.getErrorByCode(-806);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_SORT_ERROR');
const err = new Err();

DnsSecureResolverHostnameResolutionFailedError

Failed to resolve the hostname of a DNS-over-HTTPS server.

  • Name: DnsSecureResolverHostnameResolutionFailedError
  • Code: -808
  • Description: DNS_SECURE_RESOLVER_HOSTNAME_RESOLUTION_FAILED
  • Type: dns
const err = new chromiumNetErrors.DnsSecureResolverHostnameResolutionFailedError();
// or
const Err = chromiumNetErrors.getErrorByCode(-808);
const err = new Err();
// or
const Err = chromiumNetErrors.getErrorByDescription('DNS_SECURE_RESOLVER_HOSTNAME_RESOLUTION_FAILED');
const err = new Err();

Author: Maxkueng
Source Code: https://github.com/maxkueng/chromium-net-errors 
License: MIT license

#electron #node #error 

Jamal  Lemke

Jamal Lemke

1600668000

Dart DateTime 12 Hour Format AM and PM

So you want to see AM and PM in your time using the DateTime Object. It’s simple and I can explain it in 1 minute!

#dart

Gordon  Murray

Gordon Murray

1652911740

Dateable: A Dart Package to Help You with Managing Dates Easily

πŸ“† Dateable 

A Dart package to help you with managing dates easily. Can be used to store, format, convert, construct, parse and serialise dates. Calendar correctness is guaranteed by the usage of DateTime's system under the hood.

βš™οΈ Import

In your .dart files:

import 'package:dateable/dateable.dart';

βš—οΈ Usage

πŸ‘· Constructors

Variety of different constructors allows for great flexibility and interoperability with other types.

final date = Date(31, 12, 2019);
final date = Date.fromDateTime(DateTime(2019, 12, 31, 19, 1)); // Time of day is truncated
final date = Date.parseIso8601('2019-12-31T18:23:48.956871'); // Time of day is truncated
final date = Date.parse('31122019');
final date = Date.today();
final date = Date.yesterday();
final date = Date.tomorrow();

And a handy DateTime extension:

final date = DateTime(2019, 12, 31, 13, 26).toDate(); // Time of day is truncated

All of the above result in the same date object!

πŸ“… Getters

There are three getters. Simple and easy.

final date = Date(11, 3, 2002);
print(date.day); // Prints 11
print(date.month); // Prints 3
print(date.year); // Prints 2002

↔️ Conversion methods

Date allows for seamless and easy conversions to most commonly used representations!

final date = Date(11, 3, 2002);
final dateTime = date.toDateTime(); // Time of day is set to zeros
print(date.toIso8601()); // Prints 2002-03-11T00:00:00.000
print(date.toString()); // Prints 11032002

πŸ“Š Comparisions

Comparisions work just like in your well-known DateTime objects!

final earlier = Date(11, 3, 2002);
final later = Date(21, 9, 2004);
print(earlier.isBefore(later)); // True
print(later.isAfter(earlier)); // Also true

On top of this, there are also operators > (is after) , < (is before), <=, >= and ==.

Here comes another handy DateTime extension:

DateTime(2002, 3, 11, 14, 56, 28).isTheSameDate(Date(11, 3, 2002));

But if all you want is to check if your Date is nearby, here you are.

final date = Date(11, 3, 2002);
date.isToday();
date.isYesterday();
date.isTomorrow();

πŸ“° Formatting

You can format your Dates to Strings both with top-level constants and with String literals:

  • yyyy - 4 digit year, i.e. 1997
  • yy - 2 digit year, i.e. 97
  • mm - 2 digit month, i.e. 03
  • dd - 2 digit day, i.e. 11

Both of the below options are correct:

Date(11, 3, 2002).format([dd, '-', mm, '-', yyyy])
Date(11, 3, 2002).format(['dd', '-', 'mm', 'yyyy'])

πŸ”¨ Modifiers

Last but not least, there is a set of useful modifiers. Every Date object is immutable by default, so each of them creates a new Date object.

date.addDays(2) == date + 2 // Always true
date.subtractDays(7) == date - 7 // Also always true

You can also use the idiomatic copyWith function.

date.copyWith(day: 21, month: 9);

Sorting an Iterable of Dates chronologically is even easier:

[Date(21, 9, 2004), Date(24, 12, 2006), Date(11, 3, 2002)].sort((a, b) => a.compareTo(b));

Now the list is [Date(11, 3, 2002), Date(21, 9, 2004), Date(24, 12, 2006)].

Use this package as a library

Depend on it

Run this command:

With Dart:

 $ dart pub add dateable

With Flutter:

 $ flutter pub add dateable

This will add a line like this to your package's pubspec.yaml (and run an implicit dart pub get):

dependencies:
  dateable: ^3.0.0+3

Alternatively, your editor might support dart pub get or flutter pub get. Check the docs for your editor to learn more.

Import it

Now in your Dart code, you can use:

import 'package:dateable/dateable.dart';

example/dateable_example.dart

import 'package:dateable/dateable.dart';

void main() {
  // The most basic constructor.
  final date = Date(21, 3, 2002);

  // You can also use [fromDateTime] constructor...
  if (date == Date.fromDateTime(DateTime(2002, 3, 21))) {
    print('True!');
  }

  // ...or use an extension...
  if (date == DateTime(2002, 3, 21).toDate()) {
    print('Also true!');
  }

  // ...or parse from [String] ddmmyyyy...
  if (date == Date.parse('21032002')) {
    print('This is awesome.');
  }

  // ...or even parse from an ISO8601 [String]!
  if (date == Date.parseIso8601('2002-03-21T14:35:26.896')) {
    print('Very useful.');
  }

  // Do subtractDays and operator- have the same meaning?
  if (Date(1, 1, 2020) - 2 == Date(1, 1, 2020).subtractDays(2)) {
    print('Yes, they do!');
  }

  // The same with addDays and operator+.
  if (Date(31, 12, 2021) + 18 == Date(1, 1, 2022).addDays(17)) {
    print(':)');
  }

  // You can also use operators >, <, >=, <= and ==...
  if (Date(21, 3, 2002) < Date(21, 9, 2004)) {
    print('Spoiler: it is true.');
  }

  // ...as well as isAfter() and isBefore()!
  if (Date(21, 3, 2002).isBefore(Date(21, 9, 2004))) {
    print('This is also true.');
  }

  // Checking if [DateTime] is on the same day as your [Date]
  // is incredibly easy.
  if (DateTime(2002, 3, 11, 14, 6).isTheSameDate(Date(11, 3, 2002))) {
    print('A really nice extension.');
  }

  // Checking if the [Date] is today, tomorrow or yesterday is even easier.
  if (date.isToday() || date.isTomorrow() || date.isYesterday()) {
    print('The star is born.');
  }

  // You also gain access to [today], [tomorrow] and [yesterday] constructors.
  print(Date.yesterday().toString() +
      Date.today().toString() +
      Date.tomorrow().toString());

  // There are also some nice conversions:
  if (Date(21, 3, 2002).toDateTime() == DateTime(2002, 3, 21)) {
    print('Nice.');
  }
  if (Date(21, 3, 2002).toIso8601() == '2002-03-21T00:00:00.000') {
    print('Nice!');
  }
  if (Date(21, 3, 2002).toString() == '21032002') {
    print('<3');
  }

  // You can enjoy the copyWith function!
  if (Date(11, 3, 2002).copyWith(day: 21, month: 9) == Date(21, 9, 2002)) {
    print('Useful for short, idiomatic mutations.');
  }

  // Formatting is as easy as it gets!
  print(date.format([dd, '-', mm, '-', yyyy]));

  // Finally, due to the implementation of [Comparable] interface,
  // you can sort easily:
  final result = [Date(21, 9, 2004), Date(24, 12, 2006), Date(11, 3, 2002)];
  result.sort((a, b) => a.compareTo(b));
  print(result); // Prints [11032002, 21092004, 24122006]
}

πŸ› Contributing / bug reporting

Contributions and bug reports are welcome! Feel free to open an issue or create a pull request.

Author: SugaR256
Source Code: https://github.com/SugaR256/dateable 
License: MIT license

#flutter #dart #format #datetime 

August  Larson

August Larson

1624357980

String Format() Function in Python

To control and handle complex string formatting more efficiently

What is formatting, why is it used?

In python, there are several ways to present output. String formatting using python is one such method where it allows the user to control and handle complex string formatting more efficiently than simply printing space-separated values.There are many types of string formatting, such as padding and alignment, using dictionaries, etc. The usage of formatting techniques is not only subjected to strings. It also formats dates, numbers, signed digits, etc.

Structure of format() method

Let us look at the basic structure of how to write in string format method.

Syntax: β€˜String {} value’.format(value)

Let us look at an example:
β€˜Welcome to the {} world.’.format(β€œpython”)

Here, we have defined a string( β€˜β€™) with a placeholder( {} ) and assigned the argument of the parameter as β€œpython.” On executing the program, the value will be assigned to the placeholder, showing the output as:

#python #programming #string format() function in python #string format() function #format() #format() function