[whatwg] Attribute for holding private data for scripting

Maciej Stachowiak mjs at apple.com
Tue Apr 10 23:08:56 PDT 2007

On Apr 10, 2007, at 8:12 PM, Sam Ruby wrote:

> 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:
> http://intertwingly.net/stories/2007/04/10/test.html
> 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.

In Safari 2.0.4: Processed as HTML, it says "data" and then "".  
Processed as XHTML, it says "null" and then "data".
In Opera 9.00: Processed as HTML, it says "data" and then "null".  
Processed as XHTML, it says "null" and then "data".
In Firefox Processed as HTML, it says "data" and then "".  
Processed as XHTML, it says "data" and then "data".
In IE/Mac 5.2: Processed as HTML, it says "data" and the second alert  
does not appear. Processed as XHTML, neither alert appears.

It looks like Firefox's XHTML implementation already has the  
getAttribute extension I suggested of handling QNames.

By the way, the fact that no two of the browsers I tested treat this  
the same is a pretty clear indicator that DOM Core needs the HTML5  


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