[whatwg] defer on style, depends

Boris Zbarsky bzbarsky at MIT.EDU
Sun Feb 15 09:54:38 PST 2009

Garrett Smith wrote:
>> Because you have <script>s after your stylesheets, not just stylesheets.
>>  Really, controlled experiments are hard.  You have to hold all but one
>> variable constant.
> OK, I modified the example:
> http://localhost/jstest/block/link-img-noscript.html
> The bottom script will not load ('load' as opposed to 'run') in
> Firefox/3.0.6 until after 5 seconds.

Right.  Because you still have another script before it.

> The result shows that example.js loads 5 seconds after the initial
> page load. example.js waits for the stylesheet to load.

It waits for the first script to execute, which waits for the stylesheet 
to load.  That's not quite the same thing.

> My concern is with the recomputation you mentioned. Can you elaborate
> on that, or point me to a webpage that explains it?

Well, once a new stylesheet loads you have to redo rule matching for all 
nodes that might be affected in the document.  In practice, I believe 
current UAs will rerun the rule matching algorithm on all nodes in the 

> Question: What does IE do?

That's a really good question.  I don't have IE on hand to test with; do 

>> Well, one option is to stop worrying about micromanaging the load order and
>> assume that speculative parsing will solve your problems.... will it?
> Possibly. If the author could declare what a script depends on and let
> the implementation determine what to load and when, would that be too
> complicated?

Too complicated for whom?  The author or the implementation?


More information about the whatwg mailing list