Docs/Guides

Debugging

Stable

A small Chrome DevTools Protocol endpoint for evaluating code in a running script.

amber run --inspect and --inspect-brk are Stable (G5) for the CDP subset in docs/INSPECT_CONTRACT.md.

Usage

bash
amber run --inspect app.js
amber run --inspect-brk app.js            # wait for the client before running
amber run --inspect --inspect-port 9300 app.js

The listener binds to 127.0.0.1 (default port 9229; port 0 is rejected). It answers:

  • GET /json/version and GET /json/list.
  • Runtime.evaluate on the user isolate.
  • Runtime.runIfWaitingForDebugger and Debugger.resume, which release --inspect-brk.

Limits

This is not Chrome DevTools or the V8 inspector.

  • There are no breakpoints, stepping, or scope inspection.
  • Other CDP methods return JSON-RPC error -32601.
  • Runtime.evaluate only runs while the isolate thread is free: during the pause or between event-loop tasks. It does not interrupt a synchronous turn.
  • Results carry a description only.
  • --watch and --workers greater than 1 are rejected with --inspect.

Other tools

amber debug, amber lsp, and amber profile exist in the binary but are not in the Stable scope. See Experimental.

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