React Hooks Tutorial: How to Use Hooks in React.js App

Originally published at https://www.djamware.com

Because hooks are a new addition in React 16.8, so, make sure your create-react-app application update to the latest version. Previously, we have introduced React Hooks in Ionic Framework 4 hybrid mobile apps with beta support of React.js.

A shortcut to the steps:

Install and Create React App
Add React Router DOM
React Hooks and Axios Fetch from REST API
React Hooks and Axios Post to REST API
React Hooks and Axios Put to REST API
Run and Test the React Hooks Web App

The React Hooks let you use state and other React features without writing a class. Hooks are functions to hook into React state and lifecycle features from function components. Hooks don’t work inside classes because hooks let you use React without classes.

The following tools, frameworks, modules, and libraries are required for this tutorial:

Node.js (Recommended version)
React.js
Express.js and MongoDB REST API
Terminal (Mac/Linux) or Node Command Line (Windows)
IDE or Text Editor

We assume that you have already installed Node.js. Make sure Node.js command line is working (on Windows) or runnable in Linux/OS X terminal.

Install and Create React App

The create-react-app is a tool to create a React.js app from the command line or CLI. So you don’t need to install or configure tools like Webpack or Babel because they are preconfigured and hidden so that you can focus on the code. Open the terminal or Node.js command line then go to your React.js projects folder. We will install React.js app creator for creating a React.js app easily. For that, type this create-react-app command.

sudo npm install -g create-react-app

Now, create a React app by type this command.

create-react-app react-hooks-app

This command will create a new React app with the name `react-firestore` and this process can take minutes because all dependencies and modules also installing automatically. Next, go to the newly created app folder.

cd ./react-hooks-app

Open the project in your IDE or text editor and see the content of package.json.

"dependencies": {
  "react": "^16.9.0",
  "react-dom": "^16.9.0",
  "react-scripts": "3.1.1"
},

That React version is the version that already uses React Hooks as default. Now, `src/App.js` doesn’t use class anymore. For sanitation, run this React app for the first time by type this command.

yarn start

And here’ we go the latest React.js application that uses React Hooks with the same initial home page.

Add React Router DOM

We will use multiple pages for implementing CRUD operation for each REST API request methods. To add the required components for CRUD operation type these commands including creating a new components folder.

mkdir src/components
touch src/components/List.js
touch src/components/Create.js
touch src/components/Show.js
touch src/components/Edit.js

Next, we have to install or add the required modules like react-route-dom for routing/navigation and React Bootstrap for styling the UI.

yarn add react-route-dom
yarn add react-bootstrap bootstrap

Next, open and edit `src/index.js` then add these imports of Router and Route (react-router-dom) before the `./index.css` import.

import { BrowserRouter as Router, Route } from 'react-router-dom';

React Bootstrap component will be used in each created components individually. Unfortunately, the stylesheet or CSS does not include in the React Bootstrap installation. For that, open and edit public/index.html then include this Bootstrap CSS from CDN before the closing of

<HEAD>.

 <link
    rel="stylesheet"
    href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
    integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T"
    crossorigin="anonymous"
  />

Also, import these created components after the registerServiceWorker.

import List from './components/List';
import Edit from './components/Edit';
import Create from './components/Create';
import Show from './components/Show';

Next, add <Router> to the React.DOM render.

ReactDOM.render(
  <Router>
    <div>
      <Route render ={()=> < App />} path="/" />
      <Route render ={()=> < List />} path="/list" />
      <Route render ={()=> < Edit />} path="/edit/:id" />
      <Route render ={()=> < Create />} path="/create" />
      <Route render ={()=> < Show />} path="/show/:id" />
    </div>
  </Router>, document.getElementById('root'));

Next, we will modify `src/App.js` to be a root of application with the React Bootstrap Navigation Bar. Add these imports before the `App.css` import.

import Navbar from ‘react-bootstrap/Navbar’;
import Nav from ‘react-bootstrap/Nav’;

Replace the existing render components with React Bootstrap Nav and Navbar components.

return (
 <Navbar bg="light" expand="lg">
  <Navbar.Brand href="/">React-Hooks</Navbar.Brand>
  <Navbar.Toggle aria-controls="basic-navbar-nav" />
  <Navbar.Collapse id="basic-navbar-nav">
   <Nav className="mr-auto">
    <Nav.Link href="/">Home</Nav.Link>
    <Nav.Link href="/list">List of Products</Nav.Link>
    <Nav.Link href="/create">Add Product</Nav.Link>
   </Nav>
  </Navbar.Collapse>
 </Navbar>
);

The Navbar contains the navigation to root, list, and create routers.

React Hooks and Axios Fetch from REST API

To access or consume the REST API service, we will use Axios the promise-based HTTP client for the browser and node.js. Axios feature makes XMLHttpRequests, make HTTP requests, supports the Promise API, intercept request and response, transform request and response data, cancel requests, automatic transforms for JSON data, client-side support for protecting against XSRF. To install the Axios HTTP client library, simply run this command.

npm install --save axios

We will use an existing `src/App.js` to display a list of data that fetch from the REST API. Open and modify `src/App.js` the add the React Hooks useState and useEffect to existing React import and add imports of Axios, React Bootstrap ListGroup, Spinner, and react-router-dom `withRouter`.

import React, { useState, useEffect } from 'react';
import axios from 'axios';
import ListGroup from 'react-bootstrap/ListGroup';
import Spinner from 'react-bootstrap/Spinner';
import { withRouter } from 'react-router-dom';

Create the main function of the List with injected props.

function List(props) {

}

At the end of the file, add this export module as `withRouter` wrap the List function.

export default withRouter(List);

Next, fill the function bracket with the React Hooks useState that declare the data, setData, showLoading, setShowLoading constant variables. Also, declare a constant variable for REST API URL.

const \[data, setData\] = useState(\[\]);
const \[showLoading, setShowLoading\] = useState(true);
const
apiUrl = "http://localhost:3000/api/v1/products";

Add a React Hooks useEffect method or function that fetch data from REST API using Axios then set response to data constant variable.

useEffect(() => {
 const fetchData = async () => {
  const result = await axios(apiUrl);
  setData(result.data);
  setShowLoading(false);
 };

 fetchData();
}, \[\]);

Add a method or function to navigate to the details or show page with an ID parameter.

const showDetail = (id) => {
 props.history.push({
  pathname: '/show/' + id
 });
}

Implement the render components that contain a React Bootstrap ListGroup and Spinner which the ListGroup iterate data from the data constant of the React Hooks useState.

return (
 <div>
  {showLoading && <Spinner animation="border" role="status">
   <span className="sr-only">Loading...</span>
  </Spinner> }
  <ListGroup>
   {data.map((item, idx) => (
    <ListGroup.Item key={idx} action onClick={() => { showDetail(item.\_id) }}>{item.prod\_name}</ListGroup.Item>
   ))}
  </ListGroup>
 </div>
);

The list items in the List component are clickable and navigate to the Show Component. For that, open and edit `src/components/Show.js` then make similar imports, main function, export function, constant variables, methods, React Hooks useState, useEffect, and rendered component as List components except for this Show component only show a single data as an object. Also, use React Bootstrap Jumbotron to show details instead of ListGroup.

import React, { useState, useEffect } from 'react';
import axios from 'axios';
import Spinner from 'react-bootstrap/Spinner';
import Jumbotron from 'react-bootstrap/Jumbotron';
import Button from 'react-bootstrap/Button';
import { withRouter } from 'react-router-dom';

function Show(props) {
 const \[data, setData\] = useState({});
 const \[showLoading, setShowLoading\] = useState(true);
 
const apiUrl = "http://localhost:3000/api/v1/products/" +
props.match.params.id;

 useEffect(() => {
  setShowLoading(false);
  const fetchData = async () => {
   const result = await axios(apiUrl);
   setData(result.data);
   setShowLoading(false);
  };

  fetchData();
 }, \[\]);

 const editProduct = (id) => {
  props.history.push({
   pathname: '/edit/' + id
  });
 };

 const deleteProduct = (id) => {
  setShowLoading(true);
  const product = { prod\_name: data.prod\_name, prod\_desc: data.prod\_desc, prod\_price: parseInt(data.prod\_price) };
  axios.delete(apiUrl, product)
   .then((result) => {
    setShowLoading(false);
    props.history.push('/list')
   }).catch((error) => setShowLoading(false));
 };

 return (
  <div>
   {showLoading && <Spinner animation="border" role="status">
    <span className="sr-only">Loading...</span>
   </Spinner> }
   <Jumbotron>
    <h1>{data.prod\_name}</h1>
    <p>{data.prod\_desc}</p>
    <h2>Price: ${data.prod\_price}</h2>
    <p>
     <Button type="button" variant="primary" onClick={() => { editProduct(data.\_id) }}>Edit</Button>&nbsp;
     <Button type="button" variant="danger" onClick={() => { deleteProduct(data.\_id) }}>Delete</Button>
    </p>
   </Jumbotron>
  </div>
 );
}

export default withRouter(Show);

The methods or functions that use in this Show Component is deleting product and navigation to Edit component.

React Hooks and Axios Post to REST API

Now, we will implement React Hooks Form. The Form component will use React Bootstrap Form and Form.Group. Open and edit `src/components/Create.js` then add these imports of React Hooks useState, useEffect, Axios, React Bootstrap Spinner, Jumbotron, Form, Button, and react-router-dom `withRouter`.

import React, { useState, useEffect } from 'react';
import axios from 'axios';
import Spinner from 'react-bootstrap/Spinner';
import Jumbotron from 'react-bootstrap/Jumbotron';
import Form from 'react-bootstrap/Form';
import Button from 'react-bootstrap/Button';
import { withRouter } from 'react-router-dom';

Create main function with the injected props.

function Create(props) { }

In the end of file export that function and wrapped by `withRouter`.

export default withRouter(Create);

Declare the constant variables inside the main function bracket that implementing React Hooks useState and a REST API URL.

const \[product, setProduct\] = useState({ \_id: '', prod\_name: '', prod\_desc: '', prod\_price: 0 });
const \[showLoading, setShowLoading\] = useState(false);
const
apiUrl = "http://localhost:3000/api/v1/products";

Add a method or function to POST data to REST API using Axios then push to the Show component after successful response.

const saveProduct = (e) => {
 setShowLoading(true);
 e.preventDefault();
 const data = { prod\_name: product.prod\_name, prod\_desc: product.prod\_desc, prod\_price: parseInt(product.prod\_price) };
 axios.post(apiUrl, data)
  .then((result) => {
   setShowLoading(false);
   props.history.push('/show/' + result.data.\_id)
  }).catch((error) => setShowLoading(false));
};

Add a method or function that handles the OnChange event of the Form Input. Here, we will use a simple React Hooks style that set the state to a data or object.

const onChange = (e) => {
 e.persist();
 setProduct({...product, \[e.target.name\]: e.target.value});
}

Now, we will implement the rendered components that contain React Bootstrap Form, Form.Group, and Form.Control which is controlled by OnChange event.

return (
 <div>
  {showLoading &&
   <Spinner animation="border" role="status">
    <span className="sr-only">Loading...</span>
   </Spinner>
  }
  <Jumbotron>
   <Form onSubmit={saveProduct}>
    <Form.Group>
     <Form.Label>Product Name</Form.Label>
     <Form.Control type="text" name="prod\_name" id="prod\_name" placeholder="Enter product name" value={product.prod\_name} onChange={onChange} />
    </Form.Group>
    <Form.Group>
     <Form.Label>Product Description</Form.Label>
     <Form.Control as="textarea" name="prod\_desc" id="prod\_desc" rows="3" placeholder="Enter product description" value={product.prod\_desc} onChange={onChange} />
    </Form.Group>
    <Form.Group>
     <Form.Label>Product Price</Form.Label>
     <Form.Control type="number" name="prod\_price" id="prod\_price" placeholder="Enter product price" value={product.prod\_price} onChange={onChange} />
    </Form.Group>
    <Button variant="primary" type="submit">
     Save
    </Button>
   </Form>
  </Jumbotron>
 </div>
);

Attention: Don’t forget to add the name to the Form.Control otherwise the OnChange event function doesn’t work.

React Hooks and Axios Put to REST API

Similar to the previous React Hooks Form for POST data, the Form component for Edit data will use React Bootstrap Form and Form.Group. Open and edit `src/components/Edit.js` then add these imports of React Hooks useState, useEffect, Axios, React Bootstrap Spinner, Jumbotron, Form, Button, and react-router-dom `withRouter`.

import React, { useState, useEffect } from 'react';
import axios from 'axios';
import Spinner from 'react-bootstrap/Spinner';
import Jumbotron from 'react-bootstrap/Jumbotron';
import Form from 'react-bootstrap/Form';
import Button from 'react-bootstrap/Button';
import { withRouter } from 'react-router-dom';

Create main function with the injected props.

function Create(props) { }
In the end of file export that function and wrapped by \`withRouter\`.
export default withRouter(Create);

Declare the constant variables inside the main function bracket that implementing React Hooks useState and a REST API URL.

const \[product, setProduct\] = useState({ \_id: '', prod\_name: '', prod\_desc: '', prod\_price: 0 });
const \[showLoading, setShowLoading\] = useState(true);
const
apiUrl = "http://localhost:3000/api/v1/products/" +
props.match.params.id;

Add React Hooks useEffect to load or get data from the REST API using Axios then set the response to the product object.

useEffect(() => {
 setShowLoading(false);
 const fetchData = async () => {
  const result = await axios(apiUrl);
  setProduct(result.data);
  console.log(result.data);
  setShowLoading(false);
 };

 fetchData();
}, \[\]);

Add a method or function to PUT data to REST API using Axios then push to the Show component after successful response.

const updateProduct = (e) => {
 setShowLoading(true);
 e.preventDefault();
 const data = { prod\_name: product.prod\_name, prod\_desc: product.prod\_desc, prod\_price: parseInt(product.prod\_price) };
 axios.put(apiUrl, data)
  .then((result) => {
   setShowLoading(false);
   props.history.push('/show/' + result.data.\_id)
  }).catch((error) => setShowLoading(false));
};

Add a method or function that handles the OnChange event of the Form Input. Here, we will use a simple React Hooks style that set the state to a data or object.

const onChange = (e) => {
 e.persist();
 setProduct({...product, \[e.target.name\]: e.target.value});
}

Now, we will implement the rendered components that contain React Bootstrap Form, Form.Group, and Form.Control which is controlled by OnChange event.

return (
 <div>
  {showLoading &&
   <Spinner animation="border" role="status">
    <span className="sr-only">Loading...</span>
   </Spinner>
  }
  <Jumbotron>
   <Form onSubmit={updateProduct}>
    <Form.Group>
     <Form.Label>Product Name</Form.Label>
     <Form.Control type="text" name="prod\_name" id="prod\_name" placeholder="Enter product name" value={product.prod\_name} onChange={onChange} />
    </Form.Group>
    <Form.Group>
     <Form.Label>Product Description</Form.Label>
     <Form.Control as="textarea" name="prod\_desc" id="prod\_desc" rows="3" placeholder="Enter product description" value={product.prod\_desc} onChange={onChange} />
    </Form.Group>
    <Form.Group>
     <Form.Label>Product Price</Form.Label>
     <Form.Control type="number" name="prod\_price" id="prod\_price" placeholder="Enter product price" value={product.prod\_price} onChange={onChange} />
    </Form.Group>
    <Button variant="primary" type="submit">
     Update
    </Button>
   </Form>
  </Jumbotron>
 </div>
);

Run and Test the React Hooks Web App

Before running the React Hooks Web App, first, we have to run the MongoDB server and Node.js REST API server. Open a new Terminal tab then run the MongoDB daemon.

mongod

Open a new tab again then run the Node/Express REST API server.

nodemon

Now, you can run the React Hooks Web app in the current Terminal tab.

yarn start

That it’s, React Hooks Tutorial: How to Use Hooks in React.js App. You can find the full working source code from our GitHub.

#reactjs #javascript #web-development

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React Hooks Tutorial: How to Use Hooks in React.js App

Autumn Blick

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How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

Performance: It delivers optimal performance.
Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
UI design: React Native enables you to design simple and responsive UI for your mobile app.
3rd party plugins: This framework supports 3rd party plugins.
Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
Near-native user experience: React Native provides several native components, and these are platform agnostic.
The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

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In this article, you will learn what are hooks in React JS? and when to use react hooks? React JS is developed by Facebook in the year 2013. There are many students and the new developers who have confusion between react and hooks in react. Well, it is not different, react is a programming language and hooks is a function which is used in react programming language.
Read More:- https://infoatone.com/what-are-hooks-in-react-js/

#react #hooks in react #react hooks example #react js projects for beginners #what are hooks in react js? #when to use react hooks

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NBB: Ad-hoc CLJS Scripting on Node.js

Nbb

Not babashka. Node.js babashka!?

Ad-hoc CLJS scripting on Node.js.

Status

Experimental. Please report issues here.

Goals and features

Nbb's main goal is to make it easy to get started with ad hoc CLJS scripting on Node.js.

Additional goals and features are:

Fast startup without relying on a custom version of Node.js.
Small artifact (current size is around 1.2MB).
First class macros.
Support building small TUI apps using Reagent.
Complement babashka with libraries from the Node.js ecosystem.

Requirements

Nbb requires Node.js v12 or newer.

How does this tool work?

CLJS code is evaluated through SCI, the same interpreter that powers babashka. Because SCI works with advanced compilation, the bundle size, especially when combined with other dependencies, is smaller than what you get with self-hosted CLJS. That makes startup faster. The trade-off is that execution is less performant and that only a subset of CLJS is available (e.g. no deftype, yet).

Usage

Install nbb from NPM:

$ npm install nbb -g

Omit -g for a local install.

Try out an expression:

$ nbb -e '(+ 1 2 3)'
6

And then install some other NPM libraries to use in the script. E.g.:

$ npm install csv-parse shelljs zx

Create a script which uses the NPM libraries:

(ns script
  (:require ["csv-parse/lib/sync$default" :as csv-parse]
            ["fs" :as fs]
            ["path" :as path]
            ["shelljs$default" :as sh]
            ["term-size$default" :as term-size]
            ["zx$default" :as zx]
            ["zx$fs" :as zxfs]
            [nbb.core :refer [*file*]]))

(prn (path/resolve "."))

(prn (term-size))

(println (count (str (fs/readFileSync *file*))))

(prn (sh/ls "."))

(prn (csv-parse "foo,bar"))

(prn (zxfs/existsSync *file*))

(zx/$ #js ["ls"])

Call the script:

$ nbb script.cljs
"/private/tmp/test-script"
#js {:columns 216, :rows 47}
510
#js ["node_modules" "package-lock.json" "package.json" "script.cljs"]
#js [#js ["foo" "bar"]]
true
$ ls
node_modules
package-lock.json
package.json
script.cljs

Macros

Nbb has first class support for macros: you can define them right inside your .cljs file, like you are used to from JVM Clojure. Consider the plet macro to make working with promises more palatable:

(defmacro plet
  [bindings & body]
  (let [binding-pairs (reverse (partition 2 bindings))
        body (cons 'do body)]
    (reduce (fn [body [sym expr]]
              (let [expr (list '.resolve 'js/Promise expr)]
                (list '.then expr (list 'clojure.core/fn (vector sym)
                                        body))))
            body
            binding-pairs)))

Using this macro we can look async code more like sync code. Consider this puppeteer example:

(-> (.launch puppeteer)
      (.then (fn [browser]
               (-> (.newPage browser)
                   (.then (fn [page]
                            (-> (.goto page "https://clojure.org")
                                (.then #(.screenshot page #js{:path "screenshot.png"}))
                                (.catch #(js/console.log %))
                                (.then #(.close browser)))))))))

Using plet this becomes:

(plet [browser (.launch puppeteer)
       page (.newPage browser)
       _ (.goto page "https://clojure.org")
       _ (-> (.screenshot page #js{:path "screenshot.png"})
             (.catch #(js/console.log %)))]
      (.close browser))

See the puppeteer example for the full code.

Since v0.0.36, nbb includes promesa which is a library to deal with promises. The above plet macro is similar to promesa.core/let.

Startup time

$ time nbb -e '(+ 1 2 3)'
6
nbb -e '(+ 1 2 3)'   0.17s  user 0.02s system 109% cpu 0.168 total

The baseline startup time for a script is about 170ms seconds on my laptop. When invoked via npx this adds another 300ms or so, so for faster startup, either use a globally installed nbb or use $(npm bin)/nbb script.cljs to bypass npx.

Dependencies

NPM dependencies

Nbb does not depend on any NPM dependencies. All NPM libraries loaded by a script are resolved relative to that script. When using the Reagent module, React is resolved in the same way as any other NPM library.

Classpath

To load .cljs files from local paths or dependencies, you can use the --classpath argument. The current dir is added to the classpath automatically. So if there is a file foo/bar.cljs relative to your current dir, then you can load it via (:require [foo.bar :as fb]). Note that nbb uses the same naming conventions for namespaces and directories as other Clojure tools: foo-bar in the namespace name becomes foo_bar in the directory name.

To load dependencies from the Clojure ecosystem, you can use the Clojure CLI or babashka to download them and produce a classpath:

$ classpath="$(clojure -A:nbb -Spath -Sdeps '{:aliases {:nbb {:replace-deps {com.github.seancorfield/honeysql {:git/tag "v2.0.0-rc5" :git/sha "01c3a55"}}}}}')"

and then feed it to the --classpath argument:

$ nbb --classpath "$classpath" -e "(require '[honey.sql :as sql]) (sql/format {:select :foo :from :bar :where [:= :baz 2]})"
["SELECT foo FROM bar WHERE baz = ?" 2]

Currently nbb only reads from directories, not jar files, so you are encouraged to use git libs. Support for .jar files will be added later.

Current file

The name of the file that is currently being executed is available via nbb.core/*file* or on the metadata of vars:

(ns foo
  (:require [nbb.core :refer [*file*]]))

(prn *file*) ;; "/private/tmp/foo.cljs"

(defn f [])
(prn (:file (meta #'f))) ;; "/private/tmp/foo.cljs"

Reagent

Nbb includes reagent.core which will be lazily loaded when required. You can use this together with ink to create a TUI application:

$ npm install ink

ink-demo.cljs:

(ns ink-demo
  (:require ["ink" :refer [render Text]]
            [reagent.core :as r]))

(defonce state (r/atom 0))

(doseq [n (range 1 11)]
  (js/setTimeout #(swap! state inc) (* n 500)))

(defn hello []
  [:> Text {:color "green"} "Hello, world! " @state])

(render (r/as-element [hello]))

Promesa

Working with callbacks and promises can become tedious. Since nbb v0.0.36 the promesa.core namespace is included with the let and do! macros. An example:

(ns prom
  (:require [promesa.core :as p]))

(defn sleep [ms]
  (js/Promise.
   (fn [resolve _]
     (js/setTimeout resolve ms))))

(defn do-stuff
  []
  (p/do!
   (println "Doing stuff which takes a while")
   (sleep 1000)
   1))

(p/let [a (do-stuff)
        b (inc a)
        c (do-stuff)
        d (+ b c)]
  (prn d))

$ nbb prom.cljs
Doing stuff which takes a while
Doing stuff which takes a while
3

Also see API docs.

Js-interop

Since nbb v0.0.75 applied-science/js-interop is available:

(ns example
  (:require [applied-science.js-interop :as j]))

(def o (j/lit {:a 1 :b 2 :c {:d 1}}))

(prn (j/select-keys o [:a :b])) ;; #js {:a 1, :b 2}
(prn (j/get-in o [:c :d])) ;; 1

Most of this library is supported in nbb, except the following:

destructuring using :syms
property access using .-x notation. In nbb, you must use keywords.

See the example of what is currently supported.

Examples

See the examples directory for small examples.

Also check out these projects built with nbb:

c64core: retrocompute aesthetics twitter bot
gallery.cljs: script to download walpapers from windowsonearth.org.
nbb-action-example: example of a Github action built with nbb.

API

See API documentation.

Migrating to shadow-cljs

See this gist on how to convert an nbb script or project to shadow-cljs.

Build

Prequisites:

babashka >= 0.4.0
Clojure CLI >= 1.10.3.933
Node.js 16.5.0 (lower version may work, but this is the one I used to build)

To build:

Clone and cd into this repo
bb release

Run bb tasks for more project-related tasks.

Download Details:
Author: borkdude
Download Link: Download The Source Code
Official Website: https://github.com/borkdude/nbb
License: EPL-1.0

#node #javascript

AppClues Infotech

1625050361

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