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[whatwg] Questions on error handling in web workers

From: David Levin <levin@chromium.org>
Date: Wed, 15 Jun 2011 22:23:03 -0700
Message-ID: <BANLkTim8nE4Qyij56ikTRK7rjHf6kY3hpg@mail.gmail.com>
On Wed, Jul 15, 2009 at 5:17 PM, Ian Hickson <ian at hixie.ch> wrote:

> On Wed, 15 Jul 2009, Jian Li wrote:
> >
> > I have a couple questions regarding error handling in HTML 5 workers. In
> > the spec, it says "Whenever a runtime script error occurs in one of the
> > worker's scripts, if the error did not occur while handling a previous
> > script error, the user agent must report the error using the
> > WorkerGlobalScope object's onerror attribute.". Does it mean that
> > onerror attribute of WorkerContext would be called? In addition to the
> > errors being thrown?
> The term "report the error" is defined here:
>   http://www.whatwg.org/specs/web-apps/current-work/#report-the-error

The wording in the Web Workers part of the spec about what to do for onerror
has confused a number of people.

Recently, when asked about it, I thought that it should send through an
ErrorEvent when I was pointed at the spec (even though I had seen this issue

Owen Merkling added a repro case here under that assumption:

Separately, Yury Semikhatsky got it mixed up here:
And a number of us (Jian Li, etc.) were confused about it.

We can see that Ben Turner also found it confusing:

Hopefully, the spec can be clarified in this regard to avoid
incompatibilities and confusion among implementors. One possible
clarification would be a link in the onerror section for Web Workers to
indicate that they use this definition:


> > The spec also says "For dedicated workers, if the error is still not
> > handled afterwards, or if the error occurred while handling a previous
> > script error, the user agent must queue a task to fire a worker error
> > event at the Worker object associated with the worker.".  What does it
> > mean by "the error is still not handled afterwards"? Does it mean that
> > the onerror attribute is not set for WorkerContext?
> The term "not handled" is defined here:
> http://www.whatwg.org/specs/web-apps/current-work/#concept-error-nothandled
> --
> Ian Hickson               U+1047E                )\._.,--....,'``.    fL
> http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
> Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Wednesday, 15 June 2011 22:23:03 UTC

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