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React is a javascript module to make it easier to work with asynchronous code, by reducing boilerplate code and improving error and exception handling while allowing variable and task dependencies when defining flow.
The react npm package is a JavaScript library for building user interfaces, particularly for single-page applications. It allows developers to create reusable UI components and manage the state of their applications efficiently.
Component-Based Architecture
React allows developers to encapsulate UI logic and design into components, which can then be composed to build complex user interfaces.
class Welcome extends React.Component {
render() {
return <h1>Hello, {this.props.name}</h1>;
}
}
ReactDOM.render(<Welcome name='Jane' />, document.getElementById('root'));
State Management
React provides a way to manage the state within components, enabling dynamic and interactive user interfaces.
class Counter extends React.Component {
constructor(props) {
super(props);
this.state = { count: 0 };
}
increment = () => {
this.setState({ count: this.state.count + 1 });
};
render() {
return (
<div>
<p>{this.state.count}</p>
<button onClick={this.increment}>Increment</button>
</div>
);
}
}
Lifecycle Methods
React components come with lifecycle methods that are invoked at specific points in a component's lifecycle, allowing developers to hook into the component's creation, updating, and destruction processes.
class Timer extends React.Component {
componentDidMount() {
this.timerID = setInterval(() => this.tick(), 1000);
}
componentWillUnmount() {
clearInterval(this.timerID);
}
tick() {
this.setState({
date: new Date()
});
}
render() {
return (
<div>
<h2>It is {this.state.date.toLocaleTimeString()}.</h2>
</div>
);
}
}
Hooks
Hooks are functions that let developers 'hook into' React state and lifecycle features from function components. They provide a way to use stateful logic without writing a class.
import { useState, useEffect } from 'react';
function Example() {
const [count, setCount] = useState(0);
useEffect(() => {
document.title = `You clicked ${count} times`;
});
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}
Vue.js is a progressive JavaScript framework used for building user interfaces. Unlike React, which is only the view layer, Vue includes a more comprehensive set of tools for building web applications, including a routing solution and state management solution.
Angular is a platform and framework for building single-page client applications using HTML and TypeScript. Angular is more prescriptive than React, providing a standard way to structure an application and including a wide array of features out-of-the-box, such as dependency injection, templating, routing, and more.
Preact is a fast, 3kB alternative to React with the same modern API. It provides the thinnest possible Virtual DOM abstraction on top of the DOM. Preact is a good choice for when performance is critical, and the application needs to be as lightweight as possible.
Svelte is a radical new approach to building user interfaces. Whereas traditional frameworks like React and Vue do the bulk of their work in the browser, Svelte shifts that work into a compile step that happens when you build your app, resulting in significantly smaller and faster applications.
React is a javascript module to make it easier to work with asynchronous code, by reducing boilerplate code and improving error and exception handling while allowing variable and task dependencies when defining flow. This project is applying the concepts of Reactive programming or Dataflow to controlling application flow.
This async flow control module is initially designed to work with Node.js but is planned to be extended to browser and other environments.
React gets its name from similarities with how "chain reactions" work in the physical world. You start the reaction and then it cascades and continues until complete.
Also "Reactive Programming" or "Dataflow" describe defining flow which reacts to the data similar to how a spreadsheet updates cells. These are good examples of how React controls flow based on when data is available
It takes inspiration from several projects including:
The tasks can be mixed, meaning you can use async, sync, object method calls, class method calls, etc in the same flow.
Borrowing heavily from Tim and Elijah's ideas for conductor, this async flow control module provides a way to construct a flow from a collection of functions or methods (referred to as tasks in this module). It allows dependencies to be defined between the tasks so they can run in parallel as their dependencies are satisfied. React can us both variable dependencies and task dependencies.
As tasks complete, React watches the dependencies and kicks off additional tasks that have all their dependencies met and are ready to execute. This allows the flow to run at maximum speed without needing to arbitrarily block tasks into groups of parallel and serial flow.
To reduce the boilerplate code needed and improve error handling, React automatically provides callback functions for your asynchronous code. These React-provided callback functions perform these steps:
npm install react
OR
Pull from github - http://github.com/jeffbski/react
These live in the examples folder so they are ready to run. Also see test/module-use.test.js for more examples as well as the specific tests for the DSL you want to use.
### Example directly using ASTvar react = require('react');
function load(res, cb) { setTimeout(cb, 100, null, res + '-loaded'); }
function prefix(prefstr, str, cb) { setTimeout(cb, 100, null, prefstr + str); }
function postfix(str, poststr, cb) { setTimeout(cb, 100, null, str + poststr); }
function upper(str) { return str.toUpperCase(); }
var fn = react();
var errors = fn.setAndValidateAST({
inParams: ['res', 'prefstr', 'poststr'],
tasks: [
{ f: load, a: ['res'], out: ['lres'] },
{ f: upper, a: ['lres'], out: ['ulres'], type: 'ret' },
{ f: prefix, a: ['prefstr', 'ulres'], out: ['plres'] },
{ f: postfix, a: ['plres', 'poststr'], out: ['plresp'] }
],
outTask: { a: ['plresp'] }
});
console.error('errors:', errors); // []
fn('foo', 'pre-', '-post', function cb(err, lres) {
console.error('err:', err); // null
console.error('lres:', lres); // pre-FOO-LOADED-post
});
### Example using Function String DSL interface
var react = require('react');
function loadUser(uid, cb){ setTimeout(cb, 100, null, "User"+uid); }
function loadFile(filename, cb){ setTimeout(cb, 100, null, 'Filedata'+filename); }
function markdown(filedata) { return 'html'+filedata; }
function prepareDirectory(outDirname, cb){ setTimeout(cb, 200, null, 'dircreated-'+outDirname); }
function writeOutput(html, user, cb){ setTimeout(cb, 300, null, html+'_bytesWritten'); }
function loadEmailTemplate(cb) { setTimeout(cb, 50, null, 'emailmd'); }
function customizeEmail(user, emailHtml, cb) { return 'cust-'+user+emailHtml; }
function deliverEmail(custEmailHtml, cb) { setTimeout(cb, 100, null, 'delivered-'+custEmailHtml); }
function useHtml(err, html, user, bytesWritten) {
if(err) {
console.log('***Error: %s', err);
return;
}
console.log('final result: %s, user: %s, written:%s', html, user, bytesWritten);
}
var loadAndSave = react.fstrDefine('filename, uid, outDirname, cb', [ // input params
loadUser, 'uid -> err, user', // calling async fn loadUser with uid, callback is called with err and user
loadFile, 'filename -> err, filedata',
markdown, 'filedata -> returns html', // using a sync function
prepareDirectory, 'outDirname -> err, dircreated',
writeOutput, 'html, user -> err, bytesWritten', { after: prepareDirectory }, // only after prepareDirectory done
loadEmailTemplate, ' -> err, emailmd',
markdown, 'emailmd -> returns emailHtml', // using a sync function
customizeEmail, 'user, emailHtml -> returns custEmailHtml',
deliverEmail, 'custEmailHtml -> err, deliveredEmail', { after: writeOutput } // only after writeOutput is done
], 'err, html, user, bytesWritten'); // callback output params
loadAndSave('file.md', 100, '/tmp/foo', useHtml); // executing the flow
### Example using pseudocode DSL interface
var react = require('react');
function multiply(a, b, cb) { cb(null, a * b); }
function add(a, b) { return a + b; }
var locals = { // since pcodeDefine uses strings, need references to functions passed into react
multiply: multiply,
add: add
};
var fn = react.pcodeDefine('a, b, cb', [ // input params
'm := multiply(a, b)', // using a callback function, use :=
's = add(m, a)', // using a sync function, use =
'cb(err, m, s)' // output params for final callback
], locals); // hash of functions that will be used
fn(2, 3, function (err, m, s) {
console.error('err:', err); // null
console.error('m:', m); // 2 * 3 = 6
console.error('s:', s); // 6 + 2 = 8
});
### Example using jquery-like chaining DSL interface
var react = require('react');
function multiply(a, b, cb) { cb(null, a * b); }
function add(a, b) { return a + b; }
var fn = react.chainDefine()
.in('a', 'b', 'cb') // input params
.out('err', 'm', 's') // final callback output params
.async(multiply).in('a', 'b', 'cb').out('err', 'm') // task def - async fn, in params, callback out params
.sync(add).in('m', 'a').out('s') // task def - sync fn, in params, return value
.end();
fn(2, 3, function (err, m, s) {
console.error('err:', err); // null
console.error('m:', m); // 2 * 3 = 6
console.error('s:', s); // 6 + 2 = 8
});
ok ast.test.js .................... 10/10
ok cb-task.test.js ................ 31/31
ok chain.test.js .................. 56/56
ok core.test.js ................... 98/98
ok event-manager.test.js .......... 13/13
ok exec-options.test.js ............. 3/3
ok finalcb-task.test.js ............. 5/5
ok fstr.test.js ................... 64/64
ok input-parser.test.js ........... 15/15
ok module-use.test.js ............. 55/55
ok pcode.test.js .................. 65/65
ok ret-task.test.js ............... 31/31
ok task.test.js ..................... 1/1
ok validate-cb-task.test.js ......... 6/6
ok validate-ret-task.test.js ........ 7/7
ok validate.test.js ............... 26/26
ok vcon.test.js ................... 42/42
total ........................... 545/545
ok
Source code repository: http://github.com/jeffbski/react
Ideas and pull requests are encouraged - http://github.com/jeffbski/react/issues
You may contact me at @jeffbski or through github at http://github.com/jeffbski
FAQs
React is a JavaScript library for building user interfaces.
The npm package react receives a total of 24,640,734 weekly downloads. As such, react popularity was classified as popular.
We found that react demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 4 open source maintainers collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
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