JSX (JavaScript XML) is a syntax extension for JavaScript that allows developers to write HTML-like code in their React components. It is similar to a template language, but it is actually transformed into regular JavaScript at build time and can be used within the JavaScript code of a React component.
Using JSX makes it easier to write and read React code, as it allows developers to use familiar HTML syntax to describe the UI. It also makes it easier to see the structure of the UI, as the JSX code closely resembles the final rendered HTML.
Here is an example of a simple JSX element that renders a div with some text:
const element = <div>Hello, world!</div>;
JSX elements can also include attributes and children, just like HTML elements:
const element = <div className="greeting">Hello, world!</div>;
JSX elements can also include JavaScript expressions, which are enclosed in curly braces:
const name = 'Happy';
const element = <div>Hello, {name}!</div>;
JSX is not required to use React, but it is a popular and convenient way to write React components. It can be compiled to regular JavaScript using a transpiler, such as Babel.