JavaScript Compiler
Run JavaScript online in an isolated browser sandbox. See console output, errors and execution time instantly.
About the JavaScript Compiler
The JavaScript Compiler runs code in a fresh, isolated Web Worker with network access removed, so you can try snippets, algorithms and interview questions safely. console output, errors and timing appear instantly.
Your code runs in an isolated sandbox (a Web Worker in your browser, or a separate execution server for PHP), never on the web server itself.
How to use the JavaScript Compiler
- Write or paste JavaScript (or start from the sample).
- Add input in the stdin box if your code reads it with prompt() or readline().
- Click Run and read the console output, errors and execution time.
Frequently asked questions
Can my code make network requests?
No. fetch, XMLHttpRequest and WebSocket are disabled inside the sandbox, and each run has a time limit.
Which JavaScript version is supported?
Whatever your browser supports, which for current browsers includes the latest ECMAScript features such as top-level await inside async code.
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