JavaScript Playground
UI ToolsWrite and run JavaScript instantly in a browser-based sandbox with a live console output panel. Test ES2022+ syntax, algorithms, and DOM-free logic without any setup.
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About JavaScript Playground
The JavaScript Playground gives you a code editor with syntax highlighting alongside a live console output panel. Run any JavaScript snippet instantly — all console.log calls, errors, and intercepted alert()/confirm()/prompt() calls appear in the output panel. No Node.js, no build step, no install.
Features
- ✓Syntax-highlighted JavaScript editor
- ✓Live console output panel captures log, warn, error, and dir
- ✓alert(), confirm(), and prompt() intercepted and shown inline
- ✓Auto-run mode reruns code on every keystroke
- ✓Reset and Clear output buttons for a clean slate
- ✓Supports modern ES2022+ syntax including async/await
- ✓Sandboxed iframe isolates execution from the host page
Common Use Cases
- Quickly testing a JavaScript algorithm or utility function
- Exploring ES2022+ language features and syntax
- Debugging a small function in isolation
- Demonstrating JavaScript behavior in a teaching context
- Reproducing a JavaScript bug with minimal code
Frequently Asked Questions
QDoes alert() work in the JavaScript Playground?
alert(), confirm(), and prompt() are intercepted and their messages are printed to the console output panel prefixed with 📢 — they do not create browser popups.
QCan I use fetch() or async/await?
async/await and modern ES2022+ syntax are fully supported. fetch() may be blocked by CORS policies depending on the target URL.
QCan I use npm packages?
You can import packages from CDNs like esm.sh or unpkg using dynamic import() inside an async function.
QIs my code saved?
Code lives in the browser session only. Copy your snippet and save it externally — nothing is stored server-side.