[whatwg] XHTML namespace and HTML elements

[Ian Hickson]

On Tue, 30 Jun 2009, Olli Pettay wrote:
> 
> I wonder what (and where) are the reasons to use XHTML namespace also with
> HTML elements.

The main reason was simplification.

 * Consistency for scripts in HTML and XHTML. For example, a script can 
   now use createElementNS() in both without having to check the mode 
   first.

 * Consistency for CSS in HTML and XHTML.

 * Consistency for SVG features (e.g. scripting) across HTML 
   and XHTML now that we have SVG-in-HTML and SVG-in-XHTML.

 * Sanity of implementation. Browsers have had all kinds of weird 
   behaviour to act one way in text/html and another in XML while wanting 
   elements to have consistent behaviour in both.

 * A better-defined set of rules for handling mixing of XML and non-XML 
   nodes, e.g. when importing XHTML nodes from XMLHttpRequest'ed XML 
   documents into text/html documents.

...and so on.


> The behavior causes few issues like
> https://bugzilla.mozilla.org/show_bug.cgi?id=501312 and
> http://www.w3.org/Bugs/Public/show_bug.cgi?id=6777 and
> http://www.w3.org/Bugs/Public/show_bug.cgi?id=7059

These are really minor issues compared to the benefits.


> And what are the problems if and when null namespace is used with HTML 
> elements (like in <=FF3.5).

Mostly lack of consistency. Gecko actually used to do this like HTML5 
suggests, it was only changed because of a desire to match what was at the 
time thought to be the spec, if I recall correctly. HTML5 changed this 
early on precisely so that this change could be reverted.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
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