How to debug node js app with breakpoints and everything?

Question

I've installed node-inspector just to find out that it doesn't support breakpoints :| What's the point in it at all, bearing in mind that on big part node code is asynchronous and you simply cannot follow it step by step?..

I'm definitely missing a point here...

Anyway to debug node code with breakpoints and everything?

Answer 1

yupp, I've successfully used node-inspector. If you want permanent breakpoints, simply insert debugger; in your code. See http://nodejs.org/api/debugger.html.

Making node wait until a debugger is attached, using node --inspect-brk script.js (previously node --debug-brk script.js), can also be very helpful.

Answer 2

(For Node 8 and later)

Node.js has a built-in debugger. Normally you can turn on the debugger in two ways:

1. Start your Node.js app or script with the --inspect or --inspect-brk switch. For example:

   $ node.js --inspect index.js

(Note: --inspect-brk breaks before user code starts)

2. If for some reason you cannot start your Node.js app or script with the --inspect switch, you can still instruct the Node.js process to start listening for debugging messages by signalling it with SIGUSR1 (on Linux and OS X). For Node 8 and later it will activate the Inspector API, same as the --inspect switch

   $ kill -sigusr1 23485

(Note: you need to replace 23485 with your own Node.js process ID)

With the debugger turned on, you can open the Google Chrome browser, and type in the address bar chrome://inspect

Then you should see an entry listed under "Remote Target". Go ahead and click "inspect".

Now you can set breakpoints and start debugging your code.

Reference:

1. https://nodejs.org/en/docs/guides/debugging-getting-started/
2. Related issue on stackoverflow: Chrome Devtools Dedicated Node.js Inspector not stopping at breakpoints