How to debug node / express?

Question

When I start my app using 'npm start' at the command line I can browse it at :3000

.. but not when I start it using 'node app.js'

when I try 'node --debug app.js' I get a console window with the message

"Debugger listening on port 5858"

With Visual Studio and the node toolkit I get the same. With Eclipse and Enide I get the same.

I've tried using Nodes built in command line debugger, but after the debug> prompt appears issuing the continue or next step commands does nothing, and I can't browse the app at :3000

I've installed node-inspector, and after 'node --debug app.js' I can see app.js in the node-inspector chrome tab :8080, but can't browse my app at :3000 and can't get breakpoints to work.

I guess that to get debugging working I need 'node app.js' to run, and not be using 'npm start' ..

What important node configuration detail have I missed?

Why is my app not browsable when using 'node app.js' ?

Any advice is appreciated..

Answer 1

Your actually starting the app in two differnet ways using different code - one which includes the debugger and one that does not.

If your running a default Express 4 setup, if you check the package.json file you will see this section:

"scripts": {
    "start": "node ./bin/www"
  }

That is the file that is executed when you run npm start , so running node app.js is actually a different script.

If you take a look at bin/www you will see the debugger is invoked:

var debug = require('debug')('myapp');

To run use:

DEBUG=myapp ./bin/www

If you are starting using NPM, you can add it to the package.json or use exactly the same command from the cmd line:

"scripts": {
    "start": "DEBUG=myapp node ./bin/www"
  }