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Online JavaScript (Node.js) Compiler and Playground

Browser-based compiler and playground for JavaScript (Node.js) — Progsity IDE.

About JavaScript (Node.js)

JavaScript on Node.js is the default runtime for web tooling, scripting, and serverless functions. This JavaScript playground runs your code with Node semantics—require for built-ins, console.log for output—so you can test snippets that mirror production scripts.

Unlike browser-only sandboxes, you can focus on algorithms and file-less scripts without DOM APIs. The output panel captures stdout and stderr cleanly for debugging small utilities.

Use it when learning async patterns later (start with sync code here), or when you need a quick JSON transform. Sign in to save snippets you reuse in tutorials.

How to use

  1. Write top-level code using console.log. The default example prints Hello, World.
  2. If you read from stdin in advanced snippets, use the stdin panel; many simple scripts only use console.
  3. Run and iterate. stderr shows stack traces for thrown errors.

FAQ

Is this Node.js in the browser?›

Your code runs on a server-side Node-compatible runtime in our sandbox, not in the browser tab.

Can I use npm packages?›

This playground is for small scripts with built-in modules. No arbitrary npm install in Phase 1.

Is it free?›

Yes. Running JavaScript is free; saved snippets may follow account limits.

Can I save my JS code?›

Yes after sign-in. Open from your dashboard.

Compiler or playground?›

JavaScript is interpreted; you still get a compile-style error for syntax issues before the runner executes.

Related languages

Code examples

Tap “Try this” to load sample code into the editor above.

  • Parse JSON

    const raw = '{"name":"Progsity","year":2026}';
const o = JSON.parse(raw);
console.log(o.name, o.year);

  • Array map/filter

    const nums = [1, 2, 3, 4, 5];
const evens = nums.filter((n) => n % 2 === 0);
console.log(evens.map((n) => n * 2).join(","));

  • Date & ISO string

    const d = new Date("2026-04-12T00:00:00Z");
console.log(d.toISOString().slice(0, 10));

  • Closure counter

    function makeCounter() {
  let n = 0;
  return () => ++n;
}
const c = makeCounter();
console.log(c(), c(), c());