[whatwg] usemap="" and related issues

Ian Hickson ian at hixie.ch
Tue Nov 25 23:09:34 PST 2008

On Thu, 26 Jun 2008, Jonas Sicking wrote:
> > On Sat, 18 Aug 2007, Jonas Sicking wrote:
> > > Since ID is case sensitive everywhere else, I don't see a reason to make
> > > an exception from that rule here. That seems to unnecessarily complicate
> > > implementation as well as introduce weird inconsistencies for authors.
> > 
> > It already is inconsistent for usemap="". At least for legacy Web 
> > content I don't think we can do much about it. At that point, I'd 
> > rather just extend that to XHTML than to keep another difference.
> In mozilla for HTML we only look at the name attribute, and only do so 
> case insensitively. For XHTML we only look at the id attribute, and are 
> always case sensitive.
> We have had a number of bugs filed on id not working on HTML, (with most 
> of them pointing at the XHTML spec as a reason it should work) but they 
> all use the same casing for the usemap attribute and the id attribute.
> Do you have any data showing that using case sensitive matching for the 
> id attribute would break compatibility with any pages?

I do not. It seems like something where being incompatible with what IE 
does is unnecessary, though.

> What I did notice in our code though is how we deal with the case when 
> there are multiple <map>s with the same name. In this case we generally 
> use the first <map>. But if the first <map> is empty, we use the first 
> non-empty <map>. This was done for compatibility with some sites. See 
> https://bugzilla.mozilla.org/show_bug.cgi?id=264624
> I have no idea if this matters today or not.

I couldn't reproduce this behavior.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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