[whatwg] Fallback behavior

Maciej Stachowiak mjs at apple.com
Tue Mar 13 03:28:36 PDT 2007

On Mar 13, 2007, at 1:46 AM, Anne van Kesteren wrote:

> On Tue, 13 Mar 2007 00:47:23 +0100, Maciej Stachowiak  
> <mjs at apple.com> wrote:
>> As far as I can tell, the current spec does not adequately define  
>> how fallback behavior works. Specifically, what should be done  
>> with fallback content when not falling back?
>> Presumably it should be parsed into the DOM, but should not render  
>> - that's the de facto behavior. But I don't think the spec says  
>> that anywhere. Then there are weirder cases, where some element  
>> has a side effect other than rendering.
> Not render? That's really up to CSS, I'd say.

I don't think CSS can define the rules for fallback, since it has no  
way to express the fact that an element is unable to present its  
primary contents for a wide variety of possible reasons. Though I  
could imagine this if there were some :fallback pseudo-class, and the  
HTML spec defines when it applies. That's clearly not how browsers  
work currently though.

>> - should scripts in fallback content execute?
>> - should style elements in fallback content apply style?
> Currently they apply, as far as I know. I'm not sure what should  
> happen. The case that bugs me most is something like
>   <object data=foo>
>     <object data=bar>
> where foo and bar both start playing something, but you can't  
> actually see bar or turn it off...

bar shouldn't start playing in that case, should it?

  - Maciej

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