WHAT IS REACT.JS
React?(also known as?React.js?or?ReactJS) is a?free and open-source?front-end?JavaScript library[3][4]?for building?user interfaces?based on?components. It is maintained by?Meta?(formerly Facebook) and a community of individual developers and companies.[5][6][7]
React can be used to develop?single-page, mobile, or server-rendered applications with frameworks like?Next.js. Because React is only concerned with the user interface and rendering components to the?DOM, React applications often rely on libraries for routing and other client-side functionality.[8][9]
Basic usage[edit]
The following is a rudimentary example of using React for the web, written in?JSX?and JavaScript.
import React from 'react';
import ReactDOM from 'react-dom/client';
/** A pure component that displays a message */
const Greeting = () => {
return (
<div className="hello-world">
<h1>Hello, world!</h1>
</div>
);
};
/** The main app component */
const App = () => {
return <Greeting />;
};
/** React is rendered to a root element in the HTML page */
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<App />);
based on the?HTML?document below.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>React App</title>
</head>
<body>
<noscript>You need to enable JavaScript to run this app.</noscript>
<div id="root"></div>
</body>
</html>
The?Greeting?function is a React component that displays the famous introductory?''Hello, world".
When displayed in a web browser, the result will be a?