Debuggers and async/await should work together better: I have testcases.

Jason Orendorff jason.orendorff at
Fri Dec 1 16:58:02 UTC 2017


I asked around, and our debugger folks say that stepping over await should
work in current shipping Firefox. Haven't checked out your test case yet,
but someone here will.

In any case, please do report a bug! Instead of Bugzilla, report it here:

If you don't mind Slack, you can hop on this one (and ping @yulia or
@jorendorff) to talk more about async debugging:  <-- to sign up


On Fri, Dec 1, 2017 at 3:27 AM, Alex Vincent <ajvincent at> wrote:

> A few minutes ago, I released version 0.8.2 of the es7-membrane project.
> [1]  I've been using Mozilla Firefox primarily to debug it as I go, and I
> find the built-in JavaScript debugger has a few quirks when asynchronous
> functions come into the mix...
> Most notably, when I step over an "await" statement, the debugger treats
> it as if I'm exiting the function altogether.
> Also, exceptions thrown within the async functions after an await tend not
> to show up when I'm stepping through the code.
> I know I should be filing this in Bugzilla, and I will this weekend... I'm
> posting this here for all JS engine & debugging tools teams, as a
> heads-up:  when it comes to async functions, the step-through-code user
> experience is subpar.
> As for tests people can step through to see what I'm talking about:  see
> [1] for the source under docs/gui/tests.  To run the tests, type |npm run
> gui-tests|.  I use Karma to implement the tests. The karma.conf.js file in
> the root directory has a "singleRun" setting that developers can change to
> false for debugging purposes (attaching breakpoints to a test, for example).
> If it's on a weekend, I can be available to demonstrate what I'm referring
> to, or to show people how to reproduce these behaviors.
> Thanks!
> Alex Vincent
> Hayward, CA, U.S.A.
> [1]
> --
> "The first step in confirming there is a bug in someone else's work is
> confirming there are no bugs in your own."
> -- Alexander J. Vincent, June 30, 2001
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