JavaScript Runner
Write JS and hit run; captures console.log/warn/error output and shows execution time.
Executed with new Function, console output captured, never leaves the browser.
How to use
Runs your input via new Function and overrides console.log/warn/error to capture output into the panel below. Execution time is measured with performance.now().
FAQ
Why can't I use top-level const/let?
The code is wrapped in the new Function body, where const/let work fine in function scope; use a function-style return when needed.