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JavaScript Playground

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Write, run, and share code snippets — no setup required.

index.js
Output
Click Run to see the output here.

Run JavaScript online in your browser

This is a free online JavaScript playground. Write modern ES2022+ JS directly in your browser, hit Run, and execute on Node 24 or Deno 2.4 in seconds — no install, no npm, no package.json. It's the fastest way to try an Array method, test an async function, or debug a short snippet.

Under the hood, the editor uses the same engine as VS Code (JS syntax highlighting, autocompletion, error squiggles), and your code runs on Node 24 (or Deno 2.4.3) in a sandboxed container — modern ES2022+ features, Node's fs/http APIs, and Deno's standard library all available. Whether you're testing an async function, running a JSON fetch, or solving an interview problem, this online JavaScript runner goes from idea to output in seconds.

What makes this JavaScript playground useful

  • Instant JavaScript execution — write code, press Run, and see output from Node 24 (or Deno 2.4) in seconds, no setup needed.
  • Full JavaScript syntax highlighting, autocompletion, and error messages — the same editor engine that powers VS Code, right in your browser.
  • Stdin input supported — feed lines to process.stdin (Node) or the Deno readLine pattern from the playground's input box. No install — no Node, npm, or package.json to configure.
  • Deno 2.4.3 + Node 24 runtime — write modern ES2022+ JavaScript with Node APIs and Deno's standard library, no package.json needed.

What you can build in the JavaScript playground

  • Array methods (map, filter, reduce), async/await, destructuring, and modern ES2022+ idioms — run them on Node 24 or Deno 2.4.
  • Fetching and parsing JSON, promises and async flows, class syntax, and quick algorithm problems for interview practice.
  • One-off snippets — test a regex, verify a date format, try a new Array method, or confirm a tricky destructuring pattern.

Online JavaScript playground FAQ

Is the online JavaScript playground free?
Yes. The online JavaScript playground is completely free — no sign-up, no Node install, no npm setup. Open the page and run code on Node 24 or Deno 2.4.
Do I need Node.js installed to run JavaScript online?
No install required. You don't need Node, npm, or a package.json — the online JavaScript runner executes your code on Node 24 (or Deno 2.4) and returns the output in seconds.
Does the JavaScript playground work on mobile and Chromebooks?
Yes. The JavaScript playground works on any modern browser — desktop, tablet, or mobile. Great for running JS from a Chromebook, iPad, or school computer where you can't install Node.
Can I read stdin from Node in the JavaScript playground?
Yes. The playground has a stdin input box — lines you type are piped to process.stdin on Node, so readline interfaces and for await (const line of process.stdin) loops work the same way they do when you run node script.js locally and paste input at the terminal.
How do I learn JavaScript after trying the playground?
Edit the sample JavaScript, press Run, and iterate. When you want structured practice, Coddy's interactive JavaScript course takes you from variables to closures, prototypes, and async/await.