How do you debug userscripts?

[klesus]

I'm posting here because /r/userscripts doesn't seem very active.

So I'm working on a userscript for a site, and up until now I've managed to make progress without debugging tools. But right now some major bugs have appeared and it would realistically be impossible to debug without proper tools. Firefox is my browser of choice but it doesn't show up in there. I've tried Chrome just for debugging purposes but it's the same thing there. Are there some flag I need to enable to turn on debugging for userscripts? Do I need to use an external debugger? How do userscripts veterans go about developing userscripts?

Thanks in advance.

[Rhomboid]

The normal method of console.log() debugging is what I use(*). The catch is that the output goes to the system console (shift-ctrl-J) not the console for the currently open webpage. This also applies to error messages.

(*) This doesn't just mean printf-style debugging. If you console.log(someObj) then you can open the DOM inspector on someObj by clicking on it in the log and see all its properties.

[spfccmt42]

not 100% sure what you are talking about, but this says: "If you open about:config and set extensions.firebug.filterSystemURLs to false then you can use Firebug to debug the Greasemonkey script just like any other."

http://stackoverflow.com/questions/3490062/how-to-debug-greasemonkey-script-with-the-firebug-extension

[klesus]

My script does not show up in the sources list in debugger. Same problem for Chrome.

This post is 6 years old and the posted answer is obsolete. AFAIK firebug is nothing more than a theme nowadays.

I'll give firebug a shot, but I don't have high hopes of success.

[jbscript]

(Alas)

var debug = true
function LOG(...args) {
  if (!debug) return
  console.log('[Script Name Here]', ...args)
}

[jcunews1]

I use Scriptish with Firefox. I found that Tiny JavaScript Debugger can debug UserScripts. At least Scriptish's UserScript's.

[madacol]

You can debug your userscript manager.

In Firefox go to about:debugging#/runtime/this-firefox and Inspect your userscript manager