Best Practices for Debugging a Javascript Transform


I have a custom javascript transform that isn’t producing any types.

When I run SourceFile.process(), it returns no errors.

I thought I’d be able to put a breakpoint in the transform from the tools in console, but it didn’t initiate debugger.

What’s the best method for debugging something like this?


The best debugging method is the plain old logging/tracing (ask elders). First you insert at the beginning of a js file

var log = C3.logger('myLogger');

and then call, for example,

log.warn('## myState: {}', JSON.stringify(myState, null, 2));

If you do not want to mess with log levels, use a high enough one. I prepend ## so that I can paint such lines in my terminal. If you use a server, search your logs in Splunk.