Free React.js Lessons: Master JSX, Hooks, State & SPA Architecture | Nextsem

React.js Introduction, JSX Syntax & Virtual DOM Architecture

Welcome to the React.js & Modern Frontend Architecture Course!

1. What is React.js?

React is the world's most popular open-source JavaScript UI library created by Meta.

It uses a component-based architecture and a fast Virtual DOM diffing engine to render lightning-fast user interfaces without manual DOM queries.

2. What is JSX (JavaScript XML)?

JSX is a syntax extension for JavaScript that allows you to write HTML-like markup directly inside your JavaScript code.

⊞Code Example

function WelcomeBanner() {

const student = "Developer";

return (

<h1 className="text-2xl font-black text-emerald-400">Welcome, {student}!</h1>

<p className="text-sm text-slate-300">Ready to build reactive React applications.</p>

</div>

);

}

export default WelcomeBanner;

3. Core JSX Rules

Return a Single Root Element: Or wrap in a React Fragment (<> ... </>).

Close All Tags: Self-closing tags require a forward slash (e.g. <img />, <input />, <br />).

Use camelCase for HTML Attributes: class becomes className, for becomes htmlFor, tabindex becomes tabIndex.