[whatwg] Avoiding synchronous iframe load

Boris Zbarsky bzbarsky at MIT.EDU
Fri Oct 25 12:58:50 PDT 2013

On 10/25/13 2:42 PM, Ian Hickson wrote:
> Step 17 (after going async) can jump back to step 8.

Ah, I see.  That's pretty non-obvious.  Can we restructure this somehow 
to not have this random goto?  That might help the understandability of 
the spec here...

>> The main hard design constraint I know of here is that navigating frames
>> to about:blank via appending them to the DOM should ideally not change
>> which document scripts see in the frame (though it does in Gecko right
>> now; as I said we consider that a bug).
> Not sure exactly what case you mean here. Do you mean:
>     <iframe></iframe>
> ...or:
>     <iframe src="about:blank"></iframe>
> ...or:
>     <iframe src="about:blank?"></iframe>

I think those should all behave identically, ideally.  As long as that's 
not too complicated to specify/implement.

> Right now, this reports true per spec:
> ...but this reports false:

I think ideally both would report true.

> I don't really understand what Safari are Chrome are doing, given
> their behaviour with other values like "bogus:" which also returns true.
> Maybe "about:blank" is being treated like a bogus URL?

I expect the simplest way to do that is to not do a navigation to 
about:blank at all under some conditions.  The devil is in the details 
of the conditions.  :(

And thank you for walking through all this stuff, again.  I agree that 
this stuff is way too complicated (in terms of its web-compat behavior, 
which has knock-on effects on spec complexity), and I really appreciate 
you having taken the time to disentangle at least parts of it...


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