How to inspect Node.js applications

[ceremcem]

In browser, we have sourcemaps to debug Livescript. How do we debug in server side, with breakpoints?

[rhendric]

You might be interested in the source-map-support package and/or the Node.js debugger documentation.

[ceremcem]

For future readers: see https://github.com/ceremcem/debugging-livescript

[ceremcem]

@rhendric How do you generate your server side bundles with source maps for debugging? Please see: https://stackoverflow.com/q/63614309/1952991

[rhendric]

I personally run lsc to generate intermediate files and then bundle those with whatever bundler happens to be my favorite at the time (currently, it's Parcel). Most bundlers handle embedded source maps just fine.

Your issue looks like it might be caused by a limitation of the browserify-livescript project.

[ceremcem]

I finally managed to get the "debugger" working: https://github.com/ceremcem/debug-ls/tree/1.0.0

I didn't quite get the problem with browserify. I also tried Parcel.js but it didn't work for me either. With a bunch of work, Rollup worked well:

[determin1st]

check out a NiM extension: https://blog.june07.com/inspect-broke-my-workflow/

shortened me a debug cycle last time i used it..

PS: don't really know why source mapping is a thing :]

[ceremcem]

debug-ls is stable and works for any code that requires any external libraries except for dynamic imports. So, I'm not looking for anything new, but thanks for introducing NiM anyway :)

The solution of NiM isn't quite related with this topic because the main problem I had was that we can not debug a LiveScript code with any debugger that inspects simply a .js file:

Problem: How can we see the original source code while debugging the .js file that is generated from .ls file? It turns out the solution requires the following steps:

1. Compile all LiveScript scripts that your script would possibly requires (or imports)
2. Include source maps so that debugger could translate the .js code back into .ls code when hit to a breakpoint.

That looks simple as that. However setting up a "bundling command" for step 1 was a little bit tricky for me for a long long time.

[ceremcem]

@determin1st I just understood the value of NiM. When your source file changed, you have to:

1. Re-bundle your application.
2. Kill the current node process and restart it.
3. Close your debugger
4. Go to chrome://inspect/#devices
5. Find your application
6. Click "inspect" button.

NIM simply automates the steps 3, 4. 5, 6 and simply (re)opens the debugger window for you whenever a node process is started with --inspect parameter, thereby greatly speeds up the debugging cycles.

Thanks again.