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JSX and Babel (React Interview Essentials)

What is JSX? Simple Explanation: JSX lets you write HTML-like code inside JavaScript. It looks like HTML, but it's really JavaScript. Why It’s Useful: You don’t need to separate your HTML and JS into different files. You can easily build UI components that show and update data dynamically. Example: const element = Hello, React; This looks like HTML, but it's JSX — and React understands how to handle it. Q2: What happens to JSX behind the scenes? JSX doesn't run in the browser directly. React apps use Babel to convert JSX into regular JavaScript. Behind the scenes, this: const element = Hello, React; Becomes this: const element = React.createElement('h1', null, 'Hello, React'); This is how React builds a virtual DOM node that it uses to render things to the real DOM. Q3: What is Babel and why do we need it? Babel is a tool that translates JSX and modern JavaScript (like ES6) into plain JavaScript (ES5) that browsers can understand. Why Babel is critical: Browsers don’t understand JSX. Some older browsers don’t support the latest JavaScript syntax. Babel ensures that all your React code (JSX + modern JS) works everywhere.

Apr 22, 2025 - 02:47
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JSX and Babel (React Interview Essentials)

What is JSX?

Simple Explanation:
JSX lets you write HTML-like code inside JavaScript. It looks like HTML, but it's really JavaScript.

Why It’s Useful:

  • You don’t need to separate your HTML and JS into different files.
  • You can easily build UI components that show and update data dynamically.

Example:

const element = <h1>Hello, Reacth1>;

This looks like HTML, but it's JSX — and React understands how to handle it.

Q2: What happens to JSX behind the scenes?

JSX doesn't run in the browser directly. React apps use Babel to convert JSX into regular JavaScript.

Behind the scenes, this:

const element = <h1>Hello, Reacth1>;

Becomes this:

const element = React.createElement('h1', null, 'Hello, React');

This is how React builds a virtual DOM node that it uses to render things to the real DOM.

Q3: What is Babel and why do we need it?

Babel is a tool that translates JSX and modern JavaScript (like ES6) into plain JavaScript (ES5) that browsers can understand.

Why Babel is critical:

  • Browsers don’t understand JSX.
  • Some older browsers don’t support the latest JavaScript syntax.
  • Babel ensures that all your React code (JSX + modern JS) works everywhere.

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