How JSX Turns Into JavaScript? Behind the Scenes!

August 6, 2025

This content originally appeared on DEV Community and was authored by Subashini Mathi.G

Hey Devs!

Ever written some sweet-looking JSX and wondered, “Wait… how does this even work in the browser?”

Let’s reveal the magic trick — how JSX (that HTML-in-JavaScript syntax we all love) is converted into plain JavaScript under the hood. Spoiler: It’s not magic, it’s Babel

What is JSX, Really?
JSX (JavaScript XML) is syntactic sugar that lets us write UI code that looks like HTML, directly in our JavaScript files. It’s not valid JavaScript by itself — browsers can’t understand it. But tools like Babel compile it into React.createElement() calls, which the browser does understand.

What JSX Looks Like vs What It Becomes

JSX:
const element =

Hello, world!

;

Compiled JS:
const element = React.createElement(‘h1’, null, ‘Hello, world!’);
Yep, that neat JSX line turns into a function call that builds a React element.

Every JSX tag becomes a React.createElement()?
Even nested tags are just nested function calls.

How This Happens — Babel

Babel is the JavaScript compiler that takes your JSX code and transpiles it into valid JS. It’s usually bundled in tools like Create React App, Vite, or Next.js — so you rarely see this step happening.

You can even try it yourself at Babel’s online REPL — paste JSX on the left, see JavaScript on the right!

Why Should You Care?
Understanding JSX conversion is super important when:
Debugging tricky UI errors
Writing custom Babel plugins or working on advanced React tooling
Explaining React internals in interviews or blog posts
Optimizing rendering logic in performance-critical apps

JSX might look like HTML, but it’s just a fancy way of calling React.createElement(). Thanks to Babel, it’s seamlessly transformed into JS that browsers can understand.

So next time you write:
(jsx)
… remember that it’s just another function call in disguise