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JavaScript Sandbox

Run JavaScript safely in a sandboxed iframe. Console output appears below.

// Click Run to execute your code. Console output will appear here.

About this tool

Run JavaScript code safely in an isolated browser sandbox - no Node.js required. Test snippets, debug logic, experiment with Web APIs, and evaluate expressions instantly. Output appears in the console panel. Supports ES2022 features including optional chaining, nullish coalescing, top-level await, and Array.at().

How to Use the JavaScript Sandbox

  1. 1Type or paste your JavaScript code in the editor panel.
  2. 2Press Ctrl+Enter (or the Run button) to execute.
  3. 3Console output (log, warn, error) appears in the panel below.
  4. 4Use console.log() to inspect values and debug your logic.
  5. 5Click 'Clear' to reset the console and start fresh.

Frequently Asked Questions

Is the JS sandbox safe to run untrusted code?+
The sandbox runs in an isolated iframe with restricted access. It cannot access your browser's localStorage, cookies, or make cross-origin requests. It's safe for testing your own code, but don't paste code from unknown sources without reviewing it first.
Can I use npm packages in the sandbox?+
You can import packages via CDN URLs using import() syntax: const _ = await import('https://cdn.skypack.dev/lodash'). This loads the package from a CDN rather than npm install.
What is the difference between this and the browser console?+
The browser console exposes your current page's scope and can manipulate the DOM. This sandbox is a clean isolated environment with no page context - better for testing pure logic without side effects on a live page.
Does it support async/await?+
Yes. Top-level await is supported - you can write await fetch(...) directly without wrapping in an async function. This makes testing APIs and async operations much simpler.
Looking for a deeper guide on this topic? Browse the Searchlight blog.
Visit the blog โ†’

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