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JavaScript Playground

A persistent JavaScript playground — write code, run it with Ctrl+Enter, and see console output side by side.

Last updated: May 29, 2026

Client-Side Processing
Input Data Stays on Device
Instant Local Execution
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What is JavaScript Playground?

JavaScript Playground is a persistent in-browser code editor paired with a console output panel. Unlike a simple tester, it auto-saves your code to localStorage between sessions, accumulates run history, and supports Ctrl+Enter as a keyboard shortcut. Code runs in the current browser tab context using the browser's native JavaScript engine, so all modern ES6+ syntax and browser APIs are available.

How to Use JavaScript Playground

1

Write or paste JavaScript in the editor.

2

Press Ctrl+Enter or click Run.

3

See console output in the right panel.

4

Code auto-saves — return any time to continue.

Common Use Cases

  • Experimenting with JavaScript algorithms and data structures.
  • Testing array/object manipulation patterns before using in a project.
  • Learning JavaScript with instant feedback on expressions and functions.
  • Quickly verifying async behavior, closures, or prototype patterns.

Example Input and Output

A filter + map chain is written and run, logging results to the console.

JavaScript
const nums = [1,2,3,4,5];
console.log(nums.filter(n => n % 2 === 0).map(n => n * 10));
Console output
[20, 40]

Privacy

Code runs and is stored locally in your browser only.

Frequently Asked Questions

Is my code saved between visits?

Yes. Code is automatically saved to your browser's localStorage after a short pause. It will be there the next time you open this page in the same browser.

Does it support async/await?

Wrap async code in an immediately-invoked async function: (async () => { const res = await fetch(url); console.log(await res.json()); })();

Is my code uploaded anywhere?

No. Code runs and saves entirely in your browser.

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