[whatwg] <object>, type, and fallback

Simon Pieters simonp at opera.com
Mon Dec 5 23:06:42 PST 2011

On Mon, 05 Dec 2011 22:19:33 +0100, Brady Eidson <beidson at apple.com> wrote:

> I can't find a definitive answer for the following scenario:
> 1 - A page has a plug-in with fallback specified as follows:
> <object type="application/x-shockwave-flash">
> <param name="movie" value="Example.swf"/>
>     <img src="Fallback.png">
> </object>
> 2 - The page is loaded, the browser instantiates the plug-in, and the  
> plug-in content is shown.
> 3 - A script later comes along and dynamically changes the <object>'s  
> type attribute to "application/some-unsupported-type"
> Should the browser dynamically and immediately switch from the plug-in  
> to the fallback image?
> If not, what should it do?
> And is this specified anywhere?
> Thanks,
> ~Brady

"... when neither its classid attribute nor its data attribute are  
present, whenever its type attribute is set, changed, or removed: the user  
agent must queue a task to run the following steps to (re)determine what  
the object element represents. The task source for this task is the DOM  
manipulation task source."


The algorithm then determines in step 5 that there's no suitable plugin,  
and falls back.

Simon Pieters
Opera Software

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