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

Frequently asked questions

Can I use JavaScript REPL to test a regex against sample data interactively?

Yes. JavaScript REPL can test a regex against sample data interactively, directly in your browser.

Can I use JavaScript REPL to explore an API response object in a live console?

Yes. JavaScript REPL can explore an API response object in a live console, directly in your browser.

Can I use JavaScript REPL to debug async/await code without a local environment?

Yes. JavaScript REPL can debug async/await code without a local environment, directly in your browser.

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.