874788 - Allow WebIDL proxy objects to emulate undefined

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Comment 1

[Boris Zbarsky [:bzbarsky]]

This is going to need JS engine support.

This object needs to be a proxy _and_ emulate undefined, which we don't support right now in the JS engine.

Comment 2

[Boris Zbarsky [:bzbarsky]]

It's conceivable that the right answer is a new proxy JSClass that sets the relevant bit, or something...  Certainly seems like the path of least resistance.  Ccing some people who know proxies.

Comment 3

[Boris Zbarsky [:bzbarsky]]

I guess another option is to add a proxy trap for this and have EmulatesUndefined() call that as needed, since we always send proxies through the slow OOL path for this stuff anyway?

Comment 4

[Luke Wagner [:luke]]

I think Waldo added the undefined emulation, so probably the right one to ask about this.

Comment 5

[Boris Zbarsky [:bzbarsky]]

Eric made this possible in bug 924720.

Comment 6

[Boris Zbarsky [:bzbarsky]]

Attachment: Allow WebIDL HTMLAllCollection to emulate undefined.

Comment 7

[Boris Zbarsky [:bzbarsky]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/05d5f2815f92

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/05d5f2815f92