How to attach the debugger when running a script?

[csalmeida]

Hi all,

I was trying to debug a script recently but I couldn't find out how to attach the debugger to pause execution and inspect a few values.

Considering the Node script below, I would typically run node inspect script.js and it would open the debugger:

function greet(greeting) {
  debugger
  console.log("Hello,", greeting)
}

greet("World")

Is there a way to do the same with ts-node?

function greet(greeting: string): void {
  debugger;
  console.log("Hello,", greeting);
}

greet("World");

The debugger in Node looks like this:

node inspect script.js
< Debugger listening on ws://127.0.0.1:9229/c463687b-89a9-4657-bc67-2df665347327
< For help, see: https://nodejs.org/en/docs/inspector
<
< Debugger attached.
<
 ok
Break on start in script.js:6
  4 }
  5
> 6 greet("World")
debug>

Any advice on how to get this working would be much appreciated. 🙏

[agammann]

For a CommonJS ts-node setup, start Node with the inspector and preload ts-node's require hook:

node --inspect-brk -r ts-node/register script.ts

The Node flag belongs before the script. --inspect-brk pauses at startup so you have time to attach; the debugger; statement in greet provides the next pause. Attach through Chrome's chrome://inspect or your editor's Node debugger, then resume execution.

I tested that command's inspector setup with ts-node 10.9.2 / TypeScript 5.9.3 and Node 24.19.0: attached to the real inspector, resumed the startup pause, paused at debugger, and read greeting === 'World' from the paused frame. This is for CommonJS registration; ESM needs ts-node's ESM loader instead of -r ts-node/register. ts-node debugging documentation.