JavaScript REPL Terminal

Run JavaScript directly in your browser inside a sandboxed Web Worker. Top-level await, ESM imports, console capture, persistent history, and a full terminal UI. No install, no backend.

js-repl — browser

Loading terminal…

Examples

Click Load to paste into the terminal, or ▶ Run to paste and execute immediately.

About this tool

This REPL runs your JavaScript in a Web Worker — sandboxed away from the page DOM. Variables persist across commands, exactly like a Node.js or browser console REPL. const and let are automatically rewritten to var so they can be reassigned in later commands.

Features

Top-level await — let r = await fetch('https://api.github.com').then(r => r.json())
Dynamic ESM imports — const _ = (await import('https://esm.sh/lodash')).default
Console capture — log, warn, error, info, debug, table all shown inline
Persistent history — 200 entries saved to localStorage, restored on reload
Full keyboard editing — ← → Home End, ↑ ↓ history, Ctrl+C / Ctrl+L
Paste support — paste multi-line code and run it as one block

Tips

Use let or const freely — they're rewritten to var so variables persist across commands
Type help() to see the full command reference and example snippets
Press Ctrl+L or type clear() to clear the screen