[whatwg] Fallback behavior

Mihai Sucan mihai.sucan at gmail.com
Tue Mar 13 06:13:08 PDT 2007

Le Tue, 13 Mar 2007 13:21:14 +0200, Anne van Kesteren <annevk at opera.com> a  

> Not sure. Should
>    <object data=foo>
>      <img src=bar onload=alert('x')>
> show a modal dialog?

No, it should not. Fallback content should not execute (styling and  
scripts), also, fallback content should not be downloaded automatically  
(in the given example: "bar" should not download).

However, if <object data=foo> is not supported by the UA, then the  
fallback content must execute (styling and scripts), and, obviously, the  
"bar" image must be displayed (given UA support for such capabilities).

Last, but not least, the DOM must contain the fallback content as well. In  
the above example, <img> must be a child node of the <object> node.

UAs that have no support for the <object> and thus choose to display the  
fallback content must also provide the <object> node in the DOM, as the  
other UAs which have support. Again, <img> must be a child node of the  
<object> node.

HTML5 should eliminate this confusion, by specifically stating the  
behaviour in the case of fallback content.

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