[whatwg] Attribute for holding private data for scripting

Sam Ruby rubys at intertwingly.net
Tue Apr 10 20:12:49 PDT 2007

Maciej Stachowiak wrote:
> On Apr 10, 2007, at 2:14 PM, Sam Ruby wrote:
>> Anne van Kesteren wrote:
>>> On Tue, 10 Apr 2007 22:41:12 +0200, Sam Ruby <rubys at intertwingly.net> 
>>> wrote:
>>>> How so?
>>> I missed the part where you wanted to change existing HTML parsers. I 
>>> thought Hixie pointed out earlier (by means of examples) why we can't 
>>> have namespace parsing in HTML. I suppose we can discuss it again...
>> It is a recurring pattern.  The first instance was "we can't allow 
>> trailing slashes in tags", which was followed up by a carefully 
>> crafted and narrow set of exceptions, which was met with "that works" 
>> and was adopted.
>> So... while it is clearly true the full extent of XML namespames will 
>> never be supported in HTML5 (and for good reason), namespace qualified 
>> attributes allow extensibility in ways that prevent collisions.
>> One of the first questions that would need to be answered: are there 
>> any existing documents on the web which would be broken if the name 
>> placed into the DOM for attributes with names containing a colon, with 
>> an apparent prefix, and one that matched an enclosing xmlns: 
>> declaration were to be changed?
> I think the problem here isn't compatibility with existing content, but 
> rather ability to use the feature in new web content while still 
> gracefully handling existing user agents. We wrote up some design 
> principles for the HTML WG based on the WHATWG's working assumptions 
> which might make this point more clear: 
> <http://esw.w3.org/topic/HTML/ProposedDesignPrinciples>. While "Don't 
> Break The Web" is a goal, so is "Degrade Gracefully".
> To give a specific example: say I make my own "mjsml" prefix with 
> namespace "http://example.org/mjsml". In HTML4 UAs, to look up an 
> "mjsml:extension" attribute using getAttribute("mjsml:extension"). In 
> HTML5 UAs, I'd have to use getAttributeNS("http://example.org/mjsml", 
> "extension"). And neither technique would work on both (at least as I 
> understand your proposal).

Here's a page I constructed, and tested on Firefox:


This page is meant to be served as application/xhtml+xml.

Can you test it and see what results you get?  Then lets discuss further.

BTW, I intentionally don't have a completed proposal at this point.  We 
need to explore what works and what doesn't work further.

> Now, we could extend getAttribute in HTML to do namespace lookup when 
> given a name containing a colon and when namespace declarations are 
> present, but then we would want to do it in XHTML as well. And using the 
> short getAttribute call instead of a longer getAttributeNS with a 
> namespace prefix might be unacceptable to XML fans.
> Regards,
> Maciej

- Sam Ruby

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