Re: [cssom] CSSNamespaceRule

On 3/19/14 4:35 AM, Simon Pieters wrote:
> OK. I don't mind that, personally, but I can imagine that it can affect
> performance. Does anyone object to implementing this?

I'd like to understand the proposed behavior a bit better.

It seems like in an editing context you fundamentally want to re-parse 
the stylesheet from scratch when inserting a namespace rule.  Or something.

Concretely, consider a stylesheet author who first inserts this rule:

   foo|bar { color: green; }

and then inserts this rule:

   @namespace bar url("something");

During the first step, parsing of the rule fails, since the namespace 
prefix is unknown; in at least some current browser implementations, and 
per the spec draft at 
the insertRule call will throw.  So doing these operations via CSSOM is 
probably not the right way to implement this editing behavior.

So are we only talking about inserting @namespace rules that define the 
default namespace for the sheet?  Because it seems to me that inserting 
one that defines the namespace for a prefix that wasn't defined before 
can't actually affect the OM, since there should be no rules using that 

Of course you could insert a rule that _redefines_ a prefix that was 
already defined by another @namespace rule in the sheet, but I'm not 
sure how useful it is in practice to support that....  If we _do_ have 
to support it, that requires storing the prefix when it's present with 
the selectors in the sheet, which is not required right now, as far as I 
can tell.


Received on Wednesday, 19 March 2014 13:56:12 UTC