Customizable and fast Dropdown Tree Select component for React

Customizable and fast Dropdown Tree Select component for React

A lightweight and fast control to render a select component that can display hierarchical tree data. In addition, the control shows the selection in pills and allows user to search the options for quick filtering and selection. Also supports displaying partially selected nodes.

React Dropdown Tree Select

A lightweight and fast control to render a select component that can display hierarchical tree data. In addition, the control shows the selection in pills and allows user to search the options for quick filtering and selection. Also supports displaying partially selected nodes.

Screenshot

Demo
Vanilla, no framework

Online demo: https://dowjones.github.io/react-dropdown-tree-select/#/story/with-vanilla-styles

With Bootstrap

Online demo: https://dowjones.github.io/react-dropdown-tree-select/#/story/with-bootstrap-styles

With Material Design

Online demo: https://dowjones.github.io/react-dropdown-tree-select/#/story/with-material-design-styles

As Single Select

Online demo: https://dowjones.github.io/react-dropdown-tree-select/#/story/simple-select

Install

As NPM package

npm i react-dropdown-tree-select

// or if using yarn
yarn add react-dropdown-tree-select

Using a CDN

You can import the standalone UMD build from a CDN such as:

<script src="https://unpkg.com/react-dropdown-tree-select/dist/react-dropdown-tree-select.js"></script>
<link href="https://unpkg.com/react-dropdown-tree-select/dist/styles.css" rel="stylesheet" />

Note: Above example will always fetch the latest version. To fetch a specific version, use https://unpkg.com/[email protected]<version>/dist/... Visit unpkg.com to see other options.

Peer Dependencies

In order to avoid version conflicts in your project, you must specify and install react, react-dom as peer dependencies. Note that NPM doesn't install peer dependencies automatically. Instead it will show you a warning message with instructions on how to install them.

If you're using the UMD builds, you'd also need to install the peer dependencies in your application:

<script src="https://unpkg.com/react/dist/react.js"></script>
<script src="https://unpkg.com/react-dom/dist/react-dom.js"></script>
Usage
import React from 'react'
import ReactDOM from 'react-dom'

import DropdownTreeSelect from 'react-dropdown-tree-select'
import 'react-dropdown-tree-select/dist/styles.css'

const data = {
  label: 'search me',
  value: 'searchme',
  children: [
    {
      label: 'search me too',
      value: 'searchmetoo',
      children: [
        {
          label: 'No one can get me',
          value: 'anonymous',
        },
      ],
    },
  ],
}

const onChange = (currentNode, selectedNodes) => {
  console.log('onChange::', currentNode, selectedNodes)
}
const onAction = (node, action) => {
  console.log('onAction::', action, node)
}
const onNodeToggle = currentNode => {
  console.log('onNodeToggle::', currentNode)
}

ReactDOM.render(
  <DropdownTreeSelect data={data} onChange={onChange} onAction={onAction} onNodeToggle={onNodeToggle} />,
  document.body
) // in real world, you'd want to render to an element, instead of body.
Props

className

Type: string

Additional classname for container. The container renders with a default classname of react-dropdown-tree-select.

clearSearchOnChange

Type: bool

Clear the input search if a node has been selected/unselected.

onChange

Type: function

Fires when a node change event occurs. Currently the following actions trigger a node change:

  • Checkbox click which checks/unchecks the item
  • Closing of pill (which unchecks the corresponding checkbox item)

Calls the handler with the current node object and all selected nodes (if any). Example:

function onChange(currentNode, selectedNodes) {
  // currentNode: { label, value, children, expanded, checked, className, ...extraProps }
  // selectedNodes: [{ label, value, children, expanded, checked, className, ...extraProps }]
}

return <DropdownTreeSelect data={data} onChange={onChange} />

onNodeToggle

Type: function

Fires when a node is expanded or collapsed.

Calls the handler with the current node object. Example:

function onNodeToggle(currentNode) {
  // currentNode: { label, value, children, expanded, checked, className, ...extraProps }
}

return <DropdownTreeSelect data={data} onNodeToggle={onNodeToggle} />

onAction

Type: function

Fires when a action is triggered. Example:

function onAction(node, action) {
  console.log('onAction::', action, node)
}

return <DropdownTreeSelect data={data} onAction={onAction} />

onFocus

Type: function

Fires when input box receives focus or the dropdown arrow is clicked. This is helpful for setting dirty or touched flags with forms.

onBlur

Type: function

Fires when input box loses focus or the dropdown arrow is clicked again (and the dropdown collapses). This is helpful for setting dirty or touched flags with forms.

data

Type: Object or Array

Data for rendering the tree select items. The object requires the following structure:

{
  label,          // required: Checkbox label
  value,          // required: Checkbox value
  children,       // optional: Array of child objects
  checked,        // optional: Initial state of checkbox. if true, checkbox is selected and corresponding pill is rendered.
  disabled,       // optional: Selectable state of checkbox. if true, the checkbox is disabled and the node is not selectable.
  expanded,       // optional: If true, the node is expanded (children of children nodes are not expanded by default unless children nodes also have expanded: true).
  className,      // optional: Additional css class for the node. This is helpful to style the nodes your way
  tagClassName,   // optional: Css class for the corresponding tag. Use this to add custom style the pill corresponding to the node.
  actions,        // optional: An array of extra action on the node (such as displaying an info icon or any custom icons/elements)
  dataset,        // optional: Allows data-* attributes to be set on the node and tag elements
  isDefaultValue, // optional: Indicate if a node is a default value. When true, the dropdown will automatically select the node(s) when there is no other selected node. Can be used on more than one node.
  ...             // optional: Any extra properties that you'd like to receive during `onChange` event
}

The action object requires the following structure:

{
  className, // required: CSS class for the node. e.g. `fa fa-info`
  title,     // optional: HTML tooltip text
  text,      // optional: Any text to be displayed. This is helpful to pass ligatures if you're using ligature fonts
  ...        // optional: Any extra properties that you'd like to receive during `onChange` event
}

An array renders a tree with multiple root level items whereas an object renders a tree with a single root element (e.g. a Select All root node).

texts

Texts to override various labels, place holders & messages used in the component. You can also use this to provide translated messages.

The texts object requires the following structure:

{
  placeholder,  // optional: The text to display as placeholder on the search box. Defaults to `Choose...`
  noMatches,    // optional: The text to display when the search does not find results in the content list. Defaults to `No matches found`
  label,        // optional: Adds `aria-labelledby` to search input when input starts with `#`, adds `aria-label` to search input when label has value (not containing '#')
  labelRemove,  // optional: The text to display for `aria-label` on tag delete buttons which is combined with `aria-labelledby` pointing to the node label. Defaults to `Remove`
}

keepTreeOnSearch

Type: bool

Displays search results as a tree instead of flattened results

keepChildrenOnSearch

Type: bool

Displays children of found nodes to allow searching for a parent node on then selecting any child node of the found node. Defaults to false

NOTE this works only in combination with keepTreeOnSearch

keepOpenOnSelect

Type: bool (default: 'false')

Keeps single selects open after selection. Defaults to false

NOTE this works only in combination with simpleSelect or radioSelect

mode

Type: string (default: multiSelect)

Defines how the dropdown is rendered / behaves

multiSelect

A multi selectable dropdown which supports tree data with parent-child relationships. This is the default mode.

hierarchical

A multi selectable dropdown which supports tree data without parent-child relationships. In this mode, selecting a node has no ripple effects on its descendants or ancestors. Subsequently, showPartiallySelected becomes a moot flag and has no effect as well.

Note that hierarchical=true negates/overrides showPartiallySelected.

simpleSelect

Turns the dropdown into a simple, single select dropdown. If you pass tree data, only immediate children are picked, grandchildren nodes are ignored.

If multiple nodes in data are selected - by setting either checked or isDefaultValue, only the first visited node stays selected.

radioSelect

Turns the dropdown into radio select dropdown.

Like simpleSelect, you can only select one value; but keeps the tree/children structure.

If multiple nodes in data are selected - by setting either checked or isDefaultValue, only the first visited node stays selected.

showPartiallySelected

Type: bool (default: false)

If set to true, shows checkboxes in a partial state when one, but not all of their children are selected. Allows styling of partially selected nodes as well, by using :indeterminate pseudo class. Simply add desired styles to .node.partial .checkbox-item:indeterminate { ... } in your CSS.

showDropdown

Type: string

Let's you choose the rendered state of the dropdown.

initial

showDropdown: initial shows the dropdown when rendered. This can be used to render the component with the dropdown open as its initial state.

always

showDropdown: always shows the dropdown when rendered, and keeps it visible at all times. Toggling dropdown is disabled.

form states (disabled|readOnly)

Type: bool (default: false)

disabled=true disables the dropdown completely. This is useful during form submit events. readOnly=true makes the dropdown read only, which means that the user can still interact with it but cannot change any of its values. This can be useful for display only forms.

id

Type: string

Specific id for container. The container renders with a default id of rdtsN where N is the count of the current component rendered.

Use to ensure a own unique id when a simple counter is not sufficient, e.g in a partial server render (SSR)

searchPredicate

Type: function

Optional search predicate to override the default case insensitive contains match on node labels. Example:

function searchPredicate(node, searchTerm) {
  return node.customData && node.customData.toLower().indexOf(searchTerm) >= 0
}

return <DropdownTreeSelect data={data} searchPredicate={searchPredicate} />

inlineSearchInput

Type: bool (default: false)

inlineSearchInput=true makes the search input renders inside the dropdown-content. This can be useful when your UX looks something like this comment.

Styling and Customization

Default styles

The component brings minimal styles for bare-bones functional rendering. It is kept purposefully minimal so that user can style/customize it completely to suit their needs.

Using WebPack

If you're using a bundler like WebPack, make sure you configure WebPack to import the default styles. To do so, simply add this rule to your WebPack config:

// allow WebPack to import/bundle styles from node_modules for this component
module: {
  rules: [
    {
      test: /\.css$/,
      use: ExtractTextPlugin.extract({
        fallback: 'style-loader',
        use: [
          {
            loader: 'css-loader',
          },
        ],
      }),
      include: /node_modules[/\\]react-dropdown-tree-select/,
    },
  ]
}

Using a CDN

You can import and place a style link directly by referencing it from a CDN.

<link href="https://unpkg.com/react-dropdown-tree-select/dist/styles.css" rel="stylesheet" />

Note: Above example will always fetch the latest version. To fetch a specific version, use https://unpkg.com/[email protected]<version>/dist/styles.css. Visit unpkg.com to see other options.

Using with other bundlers

You can reference the files from node_modules/react-dropdown-tree-select/dist/styles.css to include in your own bundle via gulp or any other bundlers you have.

Customizing styles

Once you import default styles, it is easy to add/override the provided styles to match popular frameworks. Checkout /docs folder for some examples.

Keyboard navigation

Adds navigation with arrow keys, page down/up / home/end and toggle of selection with enter. Arrow/page up/down also toggles open of dropdown if closed.

To close open dropdown escape or tab can be used and backspace can be used for deletion of tags on empty search input.

Performance

Search optimizations

  • The tree creates a flat list of nodes from hierarchical tree data to perform searches that are linear in time irrespective of the tree depth or size.
  • It also memoizes each search term, so subsequent searches are instantaneous (almost).
  • Last but not the least, the search employs progressive filtering technique where subsequent searches are performed on the previous search set. E.g., say the tree has 4000 nodes altogether and the user wants to filter nodes that contain the text: "2002". As the user enters each key press the search goes like this:
key press  : 2-----20-----200-----2002
            |     |      |       |
search set: 967   834    49      7

The search for "20" happens against the previously matched set of 967 as opposed to all 4000 nodes; "200" happens against 834 nodes and so on.

Search debouncing

The tree debounces key presses to avoid costly search calculations. The default duration is 100ms.

Virtualized rendering

The dropdown renders only visible content and skips any nodes that are going to hidden from the user. E.g., if a parent node is not expanded, there is no point in rendering children since they will not be visible anyway.

Planned feature: Use react-virtualized to take this to the next level. The search tree now uses infinite scroll, limiting search results to 100 items initially (more load seamlessly as you scroll) - this results in super fast rendering even with large number of nodes (see #80).

Reducing costly DOM manipulations

The tree tries to minimize the DOM manipulations as much as possible. E.g., during searching, the non-matching nodes are simply hidden and css adjusted on remaining to create the perception of a new filtered list. Node toggling also achieves the expand/collapse effect by manipulating css classes instead of creating new tree with filtered out nodes.

FAQ

How do I change the placeholder text?

The default placeholder is Choose.... If you want to change this to something else, you can use placeholder property to set it.

<DropdownTreeSelect texts={{ placeholder: 'Search' }} />

How do I tweak styles?

Easy style customization is one of the design goals of this component. Every visual aspect of this dropdown can be tweaked without going through extensive hacks. E.g., to change how disabled nodes appear:

.node .fa-ban {
  color: #ccc;
}

The css classes needed to override can be found by inspecting the component via developer tools (Chrome/Safari/IE/Edge/Firefox). You can also inspect the source code or look in examples.

I do not want the default styles, do I need to fork the project?

Absolutely not! Simply do not import the styles (WebPack) or include it in your html (link tags). Roughly, this is the HTML/CSS skeleton rendered by the component:

div.react-dropdown-tree-select
  div.dropdown
    a.dropdown-trigger
      span
    ul.tag-list
      li.tag-item
        input
    div.dropdown-content
      ul.root
        li.node.tree
          i.toggle.collapsed
          label
            input.checkbox-item
              span.node-label

Write your own styles from scratch or copy existing styles and tweak them. Then include your own custom styles in your project.

Pro tip: Leverage node's className, tagClassName or action's className prop to emit your own class name. Then override/add css propeties in your class. Remember that last person wins in CSS (unless specificity or !important is involved). Often times, this may suffice and may be easier then writing all the styles from the ground up.

If you believe this aspect can be improved further, feel free to raise an issue.

My question is not listed here

Find more questions and their answers in the issue tracker. If it still doesn't answer your questions, please raise an issue.

Development

Clone the git repo and install dependencies.

npm i

// or

yarn install

You can then run following scripts for local development

npm run demo  // local demo, watches and rebuilds on changes

npm test  // test your changes

npm lint  // fixes anything that can be fixed and reports remaining errors

npm run test:cov  // test coverage

Note: If your browser doesn't hot reload or reflect changes during npm run demo, then delete docs/bundle.js and try again. Before submitting final PR, run npm run build:docs to build the bundle.js file again.

Download Details:

Author: dowjones

GitHub: https://github.com/dowjones/react-dropdown-tree-select

What is JavaScript – All You Need To Know About JavaScript

What is JavaScript – All You Need To Know About JavaScript

In this article on what is JavaScript, we will learn the basic concepts of JavaScript.

After decades of improvement, JavaScript has become one of the most popular programming languages of all time. It all started in the year 1995 when Brendan Eich created JavaScript in a span of 10 days. Since then, it has seen multiple versions, updates and has grown to the next level.

Here’s a list of topics that I’ll be covering in this blog:

  1. What is JavaScript
  2. What can JavaScript do?
  3. JavaScript Frameworks
  4. The Big Picture: HTML, CSS & JavaScript
  5. Benefits of JavaScript
  6. Fundamentals of JavaScript
    VariablesConstantsData TypesObjectsArraysFunctionsConditional statementsLoopsSwitch case
What is JavaScript?

JavaScript is a high level, interpreted, programming language used to make web pages more interactive.

Have you ever thought that your website is missing something? Maybe it’s not engaging enough or it’s not as creative as you want it to be. JavaScript is that missing piece which can be used to enhance web pages, applications, etc to provide a more user-friendly experience.

What is JavaScript?

JavaScript is the language of the web, it is used to make the web look alive by adding motion to it. To be more precise, it’s a programming language that let’s you implement complex and beautiful things/design on web pages. When you notice a web page doing more than just sit there and gawk at you, you can bet that the web page is using JavaScript.

Feature of JavaScript

Scripting language and not Java: In fact, JavaScript has nothing to do with Java. Then why is it called “Java” Script? When JavaScript was first released it was called Mocha, it was later renamed to LiveScript and then to JavaScript when Netscape (founded JavaScript) and Sun did a license agreement. Object-based scripting language which supports polymorphism, encapsulation and to some extent inheritance as well.**Interpreted language: **It doesn’t have to be compiled like Java and C which require a compiler.JavaScript runs in a browser: You can run it on Google Chrome, Internet Explorer, Safari, etc. JavaScript can execute not only in the browser but also on the server and any device which has a JavaScript Engine.

What is JavaScript – Stackoverflow stats

Currently, we have 100s of programming languages and every day new languages are being created. Among these are few powerful languages that bring about big changes in the market and JavaScript is one of them.

JavaScript has always been on the list of popular programming languages. According to StackOverflow, for the 6th year in a row, JavaScript has remained the most popular and commonly used programming language.

What can JavaScript do?

JavaScript is mainly known for creating beautiful web pages & applications. An example of this is Google Maps. If you want to explore a specific map, all you have to do is click and drag with the mouse. And what sort of language could do that? You guessed it! It’s JavaScript.JavaScript can also be used in smart watches. An example of this is the popular smartwatch maker called Pebble. Pebble has created Pebble.js which is a small JavaScript Framework that allows a developer to create an application for the Pebble line of watches in JavaScript.

What is JavaScript – Applications of JavaScript
Most popular websites like Google, Facebook, Netflix, Amazon, etc make use of JavaScript to build their websites.Among things like mobile applications, digital art, web servers and server applications, JavaScript is also used to make Games. A lot of developers are building small-scale games and apps using JavaScript.## JavaScript Frameworks

One major reason for the popularity of JavaScript is the JavaScript Frameworks. Here’s a brief introduction of the most trending JavaScript frameworks :

  1. AngularJS is Google’s web development framework which provides a set of modern development and design features for rapid application development.

  2. ReactJS is another top JavaScript framework mainly maintained by Facebook and it’s behind the User Interface of Facebook and Instagram, showing off its efficiency in maintaining such high traffic applications.

What is JavaScript – JavaScript Frameworks

  1. MeteorJS is mainly used for providing back-end development. Using JavaScript on the back-end to save time and build expertise is one of the major ideas behind Meteor.

  2. jQuery can be used when you want to extend your website and make it more interactive. Companies like Google, WordPress and IBM rely on jQuery.

The Big Picture: HTML, CSS & JavaScript

Anyone familiar with JavaScript knows that it has something to do with HTML and CSS. But what is the relationship between these three? Let me explain this with an analogy.

What is JavaScript – HTML, CSS and JavaScript

Think of HTML (HyperText Markup Language) as the skeleton of the web. It is used for displaying the web.

On the other hand, CSS is like our clothes. We put on fashionable clothes to look better. Similarly, the web is quite stylish as well. It uses CSS which stands for Cascading Style Sheets for styling purpose.

Then there is JavaScript which puts life into a web page. Just like how kids move around using the skateboard, the web also motions with the help of JavaScript.

Benefits of JavaScript

There has to be a reason why so many developers love working on JavaScript. Well, there are several benefits of using JavaScript for developing web applications, here’s a few benefits:

It’s easy to learn and simple to implement. It is a weak-type programming language unlike the strong-type programming languages like Java and C++, which have strict rules for coding.

It’s all about being fast in today’s world and since JavaScript is mainly a client-side programming language, it is very fast because any code can run immediately instead of having to contact the server and wait for an answer.

Rich set of frameworks like AngularJS, ReactJS are used to build web applications and perform different tasks.

**Builds interactive websites: **We all get attracted to beautifully designed websites and JavaScript is the reason behind such attractive websites and applications.

JavaScript is an interpreted language that does not require a compiler because the web interprets JavaScript. All you need is a browser like Google Chrome or Internet Explorer and you can do all sorts of stuff in the browser.

JavaScript is platform independent and it is supported by all major browsers like Internet Explorer, Google Chrome, Mozilla Firefox, Safari, etc.

JavaScript Fundamentals

In this What is JavaScript blog, we’ll cover the following basic fundamentals of JavaScript
VariablesConstantsData TypesObjectsArraysFunctionsConditional statementsLoopsSwitch case## Variables

Variable is a name given to a memory location which acts as a container for storing data temporarily. They are nothing but reserved memory locations to store values.

What is JavaScript – Variables

To declare a variable in JavaScript use the ‘let’ keyword. For example:

let age;
age=22;

In the above example, I’ve declared a variable ‘age’ by using the ‘let’ keyword and then I’ve stored a value (22) in it. So here a memory location is assigned to the ‘age’ variable and it contains a value i.e. ’22’.

Constants

Constants are fixed values that don’t change during execution time.

To declare a constant in JavaScript use the ‘const’ keyword. For example:

const mybirthday;
mybirthday='3rd August'; 

Data types

You can assign different types of values to a variable such as a number or a string. In JavaScript, there are two categories of data types :

What is JavaScript – Data Types

Objects

An object is a standalone entity with properties and types and it is a lot like an object in real life. For example, consider a girl, whose name is Emily, age is 22 and eye-color is brown. In this example the object is the girl and her name, age and eye-color are her properties.

What is JavaScript – Objects example

Objects are variables too, but they contain many values, so instead of declaring different variables for each property, you can declare an object which stores all these properties.

To declare an object in JavaScript use the ‘let’ keyword and make sure to use curly brackets in such a way that all property-value pairs are defined within the curly brackets. For example:

let girl= {
name: 'Emily',
age: 22,
eyeColour: 'Brown'
};

In the above example, I’ve declared an object called ‘girl’ and it has 3 properties (name, age, eye colour) with values (Emily, 22, Brown).

Arrays

An array is a data structure that contains a list of elements which store multiple values in a single variable.

For example, let’s consider a scenario where you went shopping to buy art supplies. The list of items you bought can be put into an array.

What is JavaScript – Arrays example

To declare an array in JavaScript use the ‘let’ keyword with square brackets and all the array elements must be enclosed within them. For example:

let shopping=[];
shopping=['paintBrush','sprayPaint','waterColours','canvas'];

In the above example I’ve declared an array called ‘shopping’ and I’ve added four elements in it.

Also, array elements are numbered from zero. For example this is how you access the first array element:

shopping[0];		

Functions

A function is a block of organised, reusable code that is used to perform single, related action.

Let’s create a function that calculates the product of two numbers.

To declare a function in JavaScript use the ‘function’ keyword. For example:

function product(a, b) {
return a*b;
}

In the above example, I’ve declared a function called ‘product’ and I’ve passed 2 parameters to this function, ‘a’ and ‘b’ which are variables whose product is returned by this function. Now, in order to call a function and pass a value to these parameters you’ll have to follow the below syntax:

product(8,2);

In the above code snippet I’m calling the product function with a set of values (8 & 2). These are values of the variables ‘a’ and ‘b’ and they’re called as arguments to the function.

Conditional statements – if

Conditional statement is a set of rules performed if a certain condition is met. The ‘if’ statement is used to execute a block of code, only if the condition specified holds true.

What is JavaScript – if flowchart

To declare an if statement in JavaScript use the ‘if’ keyword. The syntax is:

if(condition) {
statement;
}

Now let’s look at an example:

let numbers=[1,2,1,2,3,2,3,1];
if(numbers[0]==numbers[2]) {
console.log('Correct!');
}

In the above example I’ve defined an array of numbers and then I’ve defined an if block. Within this block is a condition and a statement. The condition is ‘(numbers[0]==numbers[2])’ and the statement is ‘console.log(‘Correct!’)’. If the condition is met, only then the statement will be executed.

Conditional statements- Else if

Else statement is used to execute a block of code if the same condition is false.

What is JavaScript – Else-if flowchart

The syntax is:

if(condition) {
statement a;
}
else (condition) {
statement b;
}

Now let’s look at an example:

let numbers=[1,2,1,2,3,2,3,1];
if(numbers[0]==numbers[4] {
console.log("Correct!");
}
else {
console.log("Wrong, please try again");
}

In the above example, I’ve defined an if block as well as an else block. So if the conditions within the if block holds false then the else block gets executed. Try this for yourself and see what you get!

**Loops **

Loops are used to repeat a specific block until some end condition is met. There are three categories of loops in JavaScript :

  1. while loop
  2. do while loop
  3. for loop
While loop

While the condition is true, the code within the loop is executed.

What is JavaScript – while loop flowchart

The syntax is:

while(condition) {
loop code;
}

Now let’s look at an example:

let i=0;
while(i < 5) {
console.log("The number is " +i);
i++;
}

In the above example, I’ve defined a while loop wherein I’ve set a condition. As long as the condition holds true, the while loop is executed. Try this for yourself and see what you get!

Do while loop

This loop will first execute the code, then check the condition and while the condition holds true, execute repeatedly.

What is JavaScript – Do while loop flowchart

Refer the syntax to better understand it:

do {
loop code;
} while(condition);

This loop executes the code block once before checking if the condition is true, then it will repeat the loop as long as the condition holds true.

Now let’s look at an example:

do {
console.log("The number is " +i);
i++;
}
while(i > 5);

The above code is similar to the while loop code except, the code block within the do loop is first executed and only then the condition within the while loop is checked. If the condition holds true then the do loop is executed again.

For loop

The for loop repeatedly executes the loop code while a given condition is TRUE. It tests the condition before executing the loop body.

What is JavaScript – for loop flowchart

The syntax is:

for(begin; condition; step) {
loop code;
}

In the above syntax:

  • begin statement is executed one time before the execution of the loop code
  • condition defines the condition for executing the loop code
  • step statement is executed every time after the code block has been executed

For example:

for (i=0;i<5;i++) {
console.log("The number is " +i);
}

In the above example, I’ve defined a for loop within which I’ve defined the begin, condition and step statements. The begin statement is that ‘i=0’. After executing the begin statement the code within the for loop is executed one time. Next, the condition is checked, if ‘i<5’ then, the code within the loop is executed. After this, the last step statement (i++) is executed. Try this and see what you get!

Switch Case

The switch statement is used to perform different actions based on different conditions.

What is JavaScript – Switch case flowchart

Let’s look at the syntax for switch case:

switch(expression) {
case 1:
code block 1
break;
case 2:
code block 2
break;
default:
code block 3
break;
}

How does it work?

  • Switch expression gets evaluated once
  • Value of the expression is compared with the values of each case
  • If there is a match, the associated block of code is executed

Let’s try this with an example:

let games='football';
switch(games) {
case "throwball":
console.log("I dislike throwball!");
break;
case "football":
console.log("I love football!");
break;
case "cricket":
console.log("I'm a huge cricket fan!");
break;
default:
console.log("I like other games");
break;
}

In the above example the switch expression is ‘games’ and the value of games is ‘football’. The value of ‘games’ is compared with the value of each case. In this example it is compared to ‘throwball’, ‘cricket’ and ‘football’. The value of ‘games’ matches with the case ‘football’, therefore the code within the ‘football’ case is executed. Try this for yourself and see what you get!

With this, we come to the end of this blog. I hope you found this blog informative and I hope you have a basic understanding of JavaScript. In my next blog on JavaScript I’ll be covering in-depth concepts, so stay tuned.

Also, check out our video on JavaScript Fundamentals if you want to get started as soon as possible and don’t forget to leave a comment if you have any doubt and also, let us know whether you’d want us to create more content on JavaScript. We are listening!

JavaScript Tutorial: if-else Statement in JavaScript

JavaScript Tutorial: if-else Statement in JavaScript

This JavaScript tutorial is a step by step guide on JavaScript If Else Statements. Learn how to use If Else in javascript and also JavaScript If Else Statements. if-else Statement in JavaScript. JavaScript's conditional statements: if; if-else; nested-if; if-else-if. These statements allow you to control the flow of your program's execution based upon conditions known only during run time.

Decision Making in programming is similar to decision making in real life. In programming also we face some situations where we want a certain block of code to be executed when some condition is fulfilled.
A programming language uses control statements to control the flow of execution of the program based on certain conditions. These are used to cause the flow of execution to advance and branch based on changes to the state of a program.

JavaScript’s conditional statements:

  • if
  • if-else
  • nested-if
  • if-else-if

These statements allow you to control the flow of your program’s execution based upon conditions known only during run time.

  • if: if statement is the most simple decision making statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed otherwise not.
    Syntax:
if(condition) 
{
   // Statements to execute if
   // condition is true
}

Here, condition after evaluation will be either true or false. if statement accepts boolean values – if the value is true then it will execute the block of statements under it.
If we do not provide the curly braces ‘{‘ and ‘}’ after if( condition ) then by default if statement will consider the immediate one statement to be inside its block. For example,

if(condition)
   statement1;
   statement2;

// Here if the condition is true, if block 
// will consider only statement1 to be inside 
// its block.

Flow chart:

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If statement 

var i = 10; 

if (i > 15) 
document.write("10 is less than 15"); 

// This statement will be executed 
// as if considers one statement by default 
document.write("I am Not in if"); 

< /script> 

Output:

I am Not in if
  • if-else: The if statement alone tells us that if a condition is true it will execute a block of statements and if the condition is false it won’t. But what if we want to do something else if the condition is false. Here comes the else statement. We can use the else statement with if statement to execute a block of code when the condition is false.
    Syntax:
if (condition)
{
    // Executes this block if
    // condition is true
}
else
{
    // Executes this block if
    // condition is false
}


Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate If-else statement 

var i = 10; 

if (i < 15) 
document.write("10 is less than 15"); 
else
document.write("I am Not in if"); 

< /script> 

Output:

i is smaller than 15
  • nested-if A nested if is an if statement that is the target of another if or else. Nested if statements means an if statement inside an if statement. Yes, JavaScript allows us to nest if statements within if statements. i.e, we can place an if statement inside another if statement.
    Syntax:
if (condition1) 
{
   // Executes when condition1 is true
   if (condition2) 
   {
      // Executes when condition2 is true
   }
}

Example:

<script type = "text/javaScript"> 

// JavaScript program to illustrate nested-if statement 

var i = 10; 

if (i == 10) { 

// First if statement 
if (i < 15) 
	document.write("i is smaller than 15"); 

// Nested - if statement 
// Will only be executed if statement above 
// it is true 
if (i < 12) 
	document.write("i is smaller than 12 too"); 
else
	document.write("i is greater than 15"); 
} 
< /script> 

Output:

i is smaller than 15
i is smaller than 12 too
  • if-else-if ladder Here, a user can decide among multiple options.The if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the ladder is bypassed. If none of the conditions is true, then the final else statement will be executed.
if (condition)
    statement;
else if (condition)
    statement;
.
.
else
    statement;


Example:

<script type = "text/javaScript"> 
// JavaScript program to illustrate nested-if statement 

var i = 20; 

if (i == 10) 
document.wrte("i is 10"); 
else if (i == 15) 
document.wrte("i is 15"); 
else if (i == 20) 
document.wrte("i is 20"); 
else
document.wrte("i is not present"); 
< /script> 

Output:

i is 20

How to Retrieve full Profile of LinkedIn User using Javascript

How to Retrieve full Profile of LinkedIn User using Javascript

I am trying to retrieve the full profile (especially job history and educational qualifications) of a linkedin user via the Javascript (Fetch LinkedIn Data Using JavaScript)

Here we are fetching LinkedIn data like Username, Email and other fields using JavaScript SDK.

Here we have 2 workarounds.

  1. Configuration of linkedIn developer api
  2. Javascript Code to fetch records

Configuration of linkedIn developer api

In order to fetch records, first we need to create developer api in linkedin which will act as token/identity while fetching data from other linkedin accounts.

So to create api, navigate to https://linkedin.com/developer/apps and click on 'Create Application'.

After navigating, fill in details like name, description and other required fields and then submit.

As we submit, it will create Client ID and Client Secret shown below, which we will be using in our code while communicating to fetch records from other LinkedIn account.

Note: We need to provide localhost Url here under Oauth 2.0. I am using my localhost, but you can probably use other production URLs under Oauth 2.0 where your app is configured. It will make your api  consider the Url as trusted which fetching records.

Javascript Code to fetch records

For getting user details like first name, last name,User image can be written as,

<script type="text/javascript" src="https://platform.linkedin.com/in.js">  
    api_key: XXXXXXX //Client ID  
    onLoad: OnLinkedInFrameworkLoad //Method that will be called on page load  
    authorize: true  
</script>  
<script type="text/javascript">  
    function OnLinkedInFrameworkLoad() {  
        IN.Event.on(IN, "auth", OnLinkedInAuth);  
    }  
  
    function OnLinkedInAuth() {  
        IN.API.Profile("me").result(ShowProfileData);  
    }  
  
    function ShowProfileData(profiles) {  
        var member = profiles.values[0];  
        var id = member.id;  
        var firstName = member.firstName;  
        var lastName = member.lastName;  
        var photo = member.pictureUrl;  
        var headline = member.headline;  
        //use information captured above  
        var stringToBind = "<p>First Name: " + firstName + " <p/><p> Last Name: " + lastName + "<p/><p>User ID: " + id + " and Head Line Provided: " + headline + "<p/>"  
        document.getElementById('profiles').innerHTML = stringToBind;  
    }  
</script>    

Kindly note we need to include 'https://platform.linkedin.com/in.js' as src under script type as it will act on this Javascript SDK provided by Linkedin.

In the same way we can also fetch records of any organization with the companyid as keyword.

<head>  
    <script type="text/javascript" src="https://platform.linkedin.com/in.js">  
        api_key: XXXXXXX ////Client ID  
        onLoad: onLinkedInLoad  
        authorize: true  
    </script>  
</head>  
  
<body>  
    <div id="displayUpdates"></div>  
    <script type="text/javascript">  
        function onLinkedInLoad() {  
            IN.Event.on(IN, "auth", onLinkedInAuth);  
            console.log("On auth");  
        }  
  
        function onLinkedInAuth() {  
            var cpnyID = XXXXX; //the Company ID for which we want updates  
            IN.API.Raw("/companies/" + cpnyID + "/updates?event-type=status-update&start=0&count=10&format=json").result(displayCompanyUpdates);  
            console.log("After auth");  
        }  
  
        function displayCompanyUpdates(result) {  
            var div = document.getElementById("displayUpdates");  
            var el = "<ul>";  
            var resValues = result.values;  
            for (var i in resValues) {  
                var share = resValues[i].updateContent.companyStatusUpdate.share;  
                var isContent = share.content;  
                var isTitled = isContent,  
                    isLinked = isContent,  
                    isDescription = isContent,  
                    isThumbnail = isContent,  
                    isComment = isContent;  
                if (isTitled) {  
                    var title = isContent.title;  
                } else {  
                    var title = "News headline";  
                }  
                var comment = share.comment;  
                if (isLinked) {  
                    var link = isContent.shortenedUrl;  
                } else {  
                    var link = "#";  
                }  
                if (isDescription) {  
                    var description = isContent.description;  
                } else {  
                    var description = "No description";  
                }  
                /* 
                if (isThumbnailz) { 
                var thumbnailUrl = isContent.thumbnailUrl; 
                } else { 
                var thumbnailUrl = "http://placehold.it/60x60"; 
                } 
                */  
                if (share) {  
                    var content = "<a target='_blank' href=" + link + ">" + comment + "</a><br>";  
                    //el += "<li><img src='" + thumbnailUrl + "' alt=''>" + content + "</li>";  
                    el += "<li><div>" + content + "</div></li>";  
                }  
                console.log(share);  
            }  
            el += "</ul>";  
            document.getElementById("displayUpdates").innerHTML = el;  
        }  
    </script>  
</body>  

We can get multiple metadata while fetching records for any any organization. We can get company updates as shown below.

Conclusion

We can also fetch any company specific data like company job updates/post, total likes, comments, and number of views along with a lot of metadata we can fetch which I have shown below.

Thank you for reading !