[whatwg] Spec for handling runtime script errors doesn't seem to match reality

[Olli Pettay]

On 11/12/2012 11:55 AM, Boris Zbarsky wrote:
> Consider the attached testcase, which calls setTimeout on a window and passes in a function from a different window.
>
> When this function is then called, it throws.
>
> Gecko, WebKit, and Presto all seem to trigger the onerror handler of the window setTimeout was called on in this case.
>
> Per spec, section 7.1.3.5.1, we have:
>
>    Whenever an uncaught runtime script error occurs in one of the
>    scripts associated with a Document, the user agent must report
>    the error at the URL of the resource containing the script (as
>    established when the script was created), with the problematic
>    position (line number and column number) in that resource, in
>    the script's origin, using the onerror event handler of the
>    script's global object.
>
> But the global object is the window the function came from.  So the spec doesn't seem to match any of the above three rendering engines.  Does it
> match Trident?
>
> I ask because I'm worried about web compat here.  While I agree that what the spec says to do is the sensible thing (and in fact, I had accidentally
> switched Gecko to doing what the spec says here as part of working on something else entirely), if none of the UAs do it then there may be web content
> that relies on it not happening.  There are certainly tests in Mozilla's regression test suite that inadvertently rely on Gecko's current behavior...


First I thought the spec behavior would make more sense, but if the error is about executing something bound to
window A it would be quite surprising to get error event on window B.
But I don't feel strongly about this.


-Olli

>
> -Boris