How to debug dynamically loaded JavaScript (with jQuery) in the browser's debugger itself?

Question

A dynamically-added script is not showing up in the browser's debugger's scripts section.

Explanation:

I need to use and have used

if( someCondition == true ){
   $.getScript("myScirpt.js", function() {
       alert('Load Complete');
       myFunction();
   });
}

so that myScript.js can be dynamically loaded on meeting some condition... And myFunction can be called only after getting the whole script loaded...

But browsers are not showing the dynamically loaded myScript.js in their debugger's script section.

Is there another way round so that all of the goals may be achieved which will make one to be able to debug a dynamically-loaded script there in the browser itself?

Answer 1

You can give your dynamically loaded script a name so that it shows in the Chrome/Firefox JavaScript debugger. To do this you place a comment at the end of the script:

//# sourceURL=filename.js

This file will then show in the "Sources" tab as filename.js. In my experience you can use 's in the name but I get odd behaviour if using /'s.

Since if a domain it is not specified filename.js will appear in a folder called "(no domain)" it is convenient to specify a domain for improving the debugging experience, as an example to see a "custom" folder it is possible to use:

//# sourceURL=browsertools://custom/filename.js

A complete example follows:

window.helloWorld = function helloWorld()
{
  console.log('Hello World!');
}
//# sourceURL=browsertools://custom/helloWorld.js

For more information see: Breakpoints in Dynamic JavaScript deprecation of //@sourceurl

Answer 2

I tried using the "//# sourceURL=filename.js" that was suggested as a workaround by the OP, but it still wasn't showing up for me in the Sources panel unless it already existed in my tabs from a previous time when it produced an exception.

Coding a "debugger;" line forced it to break at that location. Then once it was in my tabs in the Sources panel, I could set breakpoints like normal and remove the "debugger;" line.

Answer 3

When trying to track this sort of thing down in IE, I open the dev tools (F12) and then find where to place the breakpoint by using the following line in the console:

debugger;myFunction();

That switches to the debugger tab where you can step into myFunction() and set the breakpoint.

Answer 4

Notice that the source file appearing in the sources tab this way will appear in the (no domain) group and, in case you want to debug it, you will need to add a debugger; line in your code, make that line be executed (usually at the start of the execution of your source file) and then add your breakpoints wherever you want.

In case you are debugging production stages, where you will probably have no debugger; lines in your code, you can make this happen by doing a local map with CharlesProxy to your "fresh copy of the source file with the debbuger line inserted".

Answer 5

You can use //# sourceURL= and //# sourceMappingURL= at the end of your script file or script tag.

NOTE: //@ sourceURL and //@ sourceMappingURL are deprecated.