[whatwg] style sheet blocking scripts

tali garsiel t_garsiel at hotmail.com
Wed Dec 9 13:42:29 PST 2009


Well, not completely.Regarding the first question- Webkit guys told me (on their IRC channel) that the don't block the parser and only block scripts that request visual information, so I'm still  confused.

> Date: Wed, 9 Dec 2009 17:01:30 +0000
> From: ian at hixie.ch
> To: t_garsiel at hotmail.com; bzbarsky at MIT.EDU
> CC: whatwg at whatwg.org
> Subject: Re: [whatwg] style sheet blocking scripts
> 
> 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.   `._.-(,_..'--(,_..'`-.;.'
 		 	   		  
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