User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0 Build ID: 20180625102006 Steps to reproduce: 1. Opened the Debugger tab in Developer Tools. 2. Opened a page with ES6 modules. Actual results: Only the ES6 module directly referenced on the page is listed in Sources. Expected results: Every ES6 module currently loaded should have been listed in Sources.

This is pretty severe as it makes it impossible to debug modern Javascript. Noteworthy is the fact that the modules show up fine if I load the page with Developer Tools closed. However breakpoints aren't active when it is closed so it is only a partial workaround. (Not sure if this falls under bug 1436580. I'm guessing not as that bug seems to discuss new features...)

Hi Pierre Ossman, Can you please give me a test case (or an exact example of website) with which I can reproduce this issue?

Simple test case. Consists of two minimal module. "first.js" always shows up, but "second.js" does not show up if Developer tools are up when the page is loading.

Just to confirm Pierre’s observation using rv 61.0.1 and rv 62.0b7 I have my main js in the root folder and all modules in a modules sub folder Sources appear fine when opening devtools, but after a page refresh only the main js appears in the source pane Only main js appears when browsing to the site with dev tools open When the js appears missing breakpoints are not active Thanks Lenan

Thank you Pierre for the test case, and sorry for the late response. I could reproduce the issue using the test case, but not every time. I hit the refresh button a few times to be able to. Reproduced on Windows 10 and ubuntu 16.04 on Firefox 62.0b12, Firefox 61.0.1 and Nightly 63.0a1 (2018-07-29). I am marking the issue as New now.

Hey Pierre, David, we just landed a fix! Could you test tomorrow on Firefox Nightly?

Tested 63.0a1 (2018-08-23) (64-bit) and seems to work well. I can see all the files and breakpoints that trigger on load now work. Nice job. :) Will this be backported?

That's great. Which version would you like it backported to?

ESR primarily, as it will be some while before that naturally gets this otherwise. But 62 and 61 would be nice as well so I can actually start using this in my normal browser. :)

That makes complete sense. I think at the moment this will be difficult to do. Fortunately, dev-edition will have support soon.