JavaScript REPL

In-browser JavaScript console with persistent history, multi-line editing, async/await support, and a sandboxed iframe execution environment.

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Click Run to execute your code.

In-browser JS console — runs in a sandboxed iframe, supports async/await and fetch. You can import npm packages by bare name (e.g. import _ from 'lodash') — bare specifiers are rewritten to esm.sh URLs, which requires internet access and only works for ESM-compatible packages.

JavaScript REPL

In-browser JavaScript console with persistent history, multi-line editing, async/await support, and a sandboxed iframe execution environment.

Common uses

  • Test a regex against sample data interactively
  • Explore an API response object in a live console
  • Debug async/await code without a local environment

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Frequently asked questions

Can I use async/await in the REPL?

Yes, async/await and fetch are supported, and you can import npm packages by bare name.

Where does the code run?

In a sandboxed iframe inside your browser tab, not on a server.

Does it keep a history of what I ran?

The console shows a running history of your inputs, results and errors for the session. Use Clear to empty it, or Reset to restart the sandbox.

Is my data uploaded to a server?

No. This tool runs entirely in your browser — your input is processed locally on your device and is never uploaded or stored on a server.