Re: [whatwg] DOMContentLoaded and stylesheets
Am 11.02.2010 01:16, schrieb Boris Zbarsky: Gecko currently does not wait on stylesheet loads to complete before firing DOMContentLoaded. They might complete before the parser is done, or they might not. Okay, my first testcase confirmed this. http://molily.de/domcontentloaded/t1-link-no-script.html But if there’s a script after the stylesheet, DOMContentLoaded always fires after the stylesheet has been loaded. The explanation I’ve found is that the parser waits for the stylesheet to load before subsequent scripts are executed. Therefore, the whole parsing is halted and DOMContentLoaded is deferred. That’s what my second testcase demonstrates: http://molily.de/domcontentloaded/t2-link-external-script.html 2. Does the HTML5 parser specify that external stylesheets defer external script execution? As far as I understand the specs, it doesn't. http://www.whatwg.org/specs/web-apps/current-work/multipage/scripting-1.html#running-a-script step 8 the cases that talk about a style sheet blocking scripts specify this. Thanks for the hint. AFAICS only the third case talks about “a style sheet blocking scripts”. But this case only deals with “parser-inserted” inline scripts. The question is: Is a normal external script “parser-inserted” or not? I assume the flag to be false, since that’s the default value and I found “parser-inserted” to be true for XML parsing only (#parsing-xhtml-documents). Correct? Just to translate from HTML5 speak into my own words. I’ve got ... link rel=stylesheet href=... script src=.../script ... and I would like to step through the parsing algorithm. This is my understanding so far: 1. Run the script (#parsing-main-incdata, case “An end tag whose tag name is script”) 2. Jump to #running-a-script 3. Fetch the external script (step 7) 4. We’ve reached step 8 which you’ve mentioned above. I assume the fourth case is true (“If the element has a src attribute”), since the script is not “parser-inserted”. 6. Once the script fetching is complete, execute the script block (“The task that the networking task source places on the task queue once the fetching algorithm has completed must execute the script block.”) 7. Jump to #executing-a-script-block 8. If the load was successful, initialize it (step 1) 9. “Pause until either any applicable style sheets have been fetched and applied, or the user agent has timed out and decided to not wait for those style sheets.” (step 2) -- I guess *this* is where the waiting happens, right? 10. Execute the script (“Create a script from the script element node”) 11. Jump back to #parsing-main-incdata 12. „if there is a pending parsing-blocking script“ -- I guess there is none. So we’re done here. The handling of inline scripts is somewhat easier: 1. Run the script (#parsing-main-incdata, case “An end tag whose tag name is script”) 2. Jump to #running-a-script 3. Step 8, Case 5 “Otherwise” (“The user agent must immediately execute the script block” 4. Jump to #executing-a-script-block 5. “If the load was successful” 6. Step 1, Initialize, “If the script is inline and the script block’s type is a text-based language”: Set text attribute 7. Step 2: “Pause until either any applicable style sheets have been fetched and applied, or the user agent has timed out and decided to not wait for those style sheets.” 8. Step 3, execute the script That means, inline script execution should also wait for stylesheets to load. Am I right in this reading? Thanks, Mathias
Re: [whatwg] DOMContentLoaded and stylesheets
On 2/11/10 9:07 AM, Mathias Schäfer wrote: But if there’s a script after the stylesheet, DOMContentLoaded always fires after the stylesheet has been loaded. The explanation I’ve found is that the parser waits for the stylesheet to load before subsequent scripts are executed. Correct. step 8 the cases that talk about a style sheet blocking scripts specify this. Thanks for the hint. AFAICS only the third case talks about “a style sheet blocking scripts”. But this case only deals with “parser-inserted” inline scripts. Ah, indeed. For non-inline scripts the relevant part is step 2 under the If the load was successful part in http://www.whatwg.org/specs/web-apps/current-work/multipage/scripting-1.html#executing-a-script-block The question is: Is a normal external script “parser-inserted” or not? Yes. I assume the flag to be false, since that’s the default value and I found “parser-inserted” to be true for XML parsing only (#parsing-xhtml-documents). Correct? No. The HTML parser state machine sets that flag in various cases. For example, http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#parsing-main-inhead under 'A start tag whose tag name is script'. link rel=stylesheet href=... script src=.../script ... and I would like to step through the parsing algorithm. This is my understanding so far: ... 4. We’ve reached step 8 which you’ve mentioned above. I assume the fourth case is true (“If the element has a src attribute”), since the script is not “parser-inserted”. The script is in fact parser-inserted, but you still land in the fourth case, I think. 9. “Pause until either any applicable style sheets have been fetched and applied, or the user agent has timed out and decided to not wait for those style sheets.” (step 2) -- I guess *this* is where the waiting happens, right? Yep. That means, inline script execution should also wait for stylesheets to load. Am I right in this reading? Yes. -Boris
Re: [whatwg] DOMContentLoaded and stylesheets
On 2/10/10 6:55 PM, Mathias Schäfer wrote: In a JavaScript tutorial, I wanted to explain what DOMContentLoaded actually does. It fires once the parser has consumed the entire input stream, such that you can rely on all the parser-created DOM nodes being present. This is true in all implementations of DOMContentLoaded. What is not consistent is the ordering of this event with the loading of various subresources. 1. Am I right that HTML5 will standardize Opera's pure DOMContentLoaded model, never waiting for stylesheets? My assumption is that this will break compatibility with the current Gecko and Webkit implementations. Gecko currently does not wait on stylesheet loads to complete before firing DOMContentLoaded. They might complete before the parser is done, or they might not. 2. Does the HTML5 parser specify that external stylesheets defer external script execution? As far as I understand the specs, it doesn't. http://www.whatwg.org/specs/web-apps/current-work/multipage/scripting-1.html#running-a-script step 8 the cases that talk about a style sheet blocking scripts specify this. I really wish those steps had individual IDs, and so did the cases inside them. It'd make it a lot easier to link to them! In Gecko and IE, the loading of stylesheets also defers the execution of subsequent *inline* scripts. I haven't found a rule for that in the HTML5 parsing algorithm either. See above. -Boris
