[whatwg] usemap="" and related issues

Jonas Sicking jonas at sicking.cc
Thu Jun 26 15:48:27 PDT 2008

> 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?

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 

I have no idea if this matters today or not.

/ Jonas

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