node-inspect-debugger

Run node inspect path/to/script.js to pause on entry, then use commands like sb('file.js', 42) to set breakpoints, cont to continue, and next or step to move through code. Use repl to evaluate local variables in the current scope.

Run node --inspect-brk --import tsx path/to/script.ts to pause before execution with TypeScript support. Add --enable-source-maps when you need breakpoints to map back to original TypeScript source lines.

Yes, send kill -SIGUSR1 <pid> to enable the inspector on a running process, then connect with node inspect -p <pid>. Confirm the target first by querying http://127.0.0.1:9229/json/list.

--inspect opens the debug port without pausing, so early code runs before you attach. Use --inspect-brk when setup must happen before any code executes, such as catching startup races.

Breakpoints miss when the file path is wrong, source maps are misconfigured, or execution already passed the line before the debugger attached. Verify the file path, enable source maps for TypeScript, and use --inspect-brk for early code.

Use the Chrome DevTools Protocol with chrome-remote-interface: enable Profiler, call start and stop, then write the result as a .cpuprofile file. For memory, enable HeapProfiler, collect addHeapSnapshotChunk events, and call takeHeapSnapshot.