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[whatwg] style sheet blocking scripts

From: Ian Hickson <ian@hixie.ch>
Date: Wed, 9 Dec 2009 17:01:30 +0000 (UTC)
Message-ID: <Pine.LNX.4.62.0912091700220.29336@hixie.dreamhostps.com>
On Wed, 28 Oct 2009, tali garsiel wrote:
> 
> This is a quote from Section 4.2 of the spec:
> 
> "A style sheet in the context of the Document of an HTML parser or XML 
> parser is said to be a style sheet blocking scripts if the element was 
> created by that Document's parser, and the element is either a style 
> element or a link element that was an external resource link that 
> contributes to the styling processing model when the element was created 
> by the parser, and the element's style sheet was enabled when the 
> element was created by the parser, and the element's style sheet ready 
> flag is not yet set, and, the last time the event loop reached step 1, 
> the element was in that Document"
> 
> And the section about parsing - the "<script>" tag says that before 
> executing a script the parser must:
> 
> 3. Spin the event loop until there is no style sheet blocking scripts 
> and the script's "ready to be parser-executed" flag is set.
> 
> I have two questions:
> 
> 1. As far as I know, Firefox and Webkit have a "stall on demand" 
> behavior, where a stylesheet blocks a script only if the script asks 
> from style information. According to the spec the style sheet always 
> blocks a script, am I right?
> 
> 2. Can you clarify the condition - "the element's style sheet was 
> enabled when the element was created by the parser, and the element's 
> style sheet ready flag is not yet set, and, the last time the event loop 
> reached step 1, the element was in that Document"
> 
> Does it mean the style sheet blocks scripts only if it's currently being 
> parsed?

On Wed, 28 Oct 2009, Boris Zbarsky wrote:
> On 10/28/09 2:59 AM, tali garsiel wrote:
> > 1. As far as I know, Firefox and Webkit have a "stall on demand" 
> > behavior, where a stylesheet blocks a script only if the script asks 
> > from style information.
> 
> You know wrong, sorry.  Firefox has the behavior the spec describes; 
> webkit blocks the parser completely on stylesheets (the behavior Firefox 
> used to have).  Last I checked, at least.
> 
> > 2. Can you clarify the condition - "the element's style sheet was 
> > enabled when the element was created by the parser, and the element's 
> > style sheet ready flag is not yet set, and, the last time the event 
> > loop reached step 1, the element was in that Document"
> 
> The parts of that condition basically mean:
> 
> 1)  When the element was created by the parser, it was in the then-enabled
> stylesheet set (i.e. not an alternate stylesheet).
> 2)  The stylesheet, or one of its @import descendants, is still loading.
> 3)  The stylesheet linking element is still in the document (so the stylesheet
> still applies).

Thanks Boris.

Tali, does this answer your question to your satisfaction?

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Wednesday, 9 December 2009 09:01:30 UTC

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