On Aug 30, 2013, at 5:54 PM, Glenn Maynard <gl...@zewt.org> wrote: > I don't like the name "jit", because it already has a different meaning when > talking about scripting. If this was for CSS or WebVTT or something else > other than scripts, it wouldn't be as bad... > > On Fri, Aug 30, 2013 at 7:22 PM, Ryosuke Niwa <rn...@apple.com> wrote: > I don't quite understand why we need two values for "whenneded". > > Why can't we simply have "prefetch" (since we already use that term in the > link element) and "needs" (I'd prefer calling it "requires") content > attributes? > > When a script element has the prefetch attribute, it doesn't execute until > execute() is called upon the element unless > (i.e. the script is executed immediately when the script has been loaded) if > at least one of its dependencies is not a prefetch > (i.e. doesn't have the "prefetch" content attribute). > > I'm not sure what you mean (skipping the parenthetical this says "unless if", > so I'm not sure how to parse that), but "prefetch" sounds like something > different than "jit".
Yes. "Prefetch" is like "noexecute" if there are no dependencies that require immediate execution. But it behaves like "jit" if there are dependencies. Example 1. <script src="A.js" prefetch></script> <script src="B.js" requires="C.js" prefetch></script> <script src="C.js" prefetch></script> Neither A.js, B.js, nor C.js are executed until execute() is called on each element. Example 2. <script src="A.js" prefetch></script> <script src="B.js" requires="C.js"></script> <script src="C.js" prefetch></script> Both C.js and B.js are executed respectively once they're loaded since C.js requires B.js. Example 2. <script src="A.js" prefetch></script> <script src="B.js" requires="C.js"></script> <script src="C.js" requires="A.js" prefetch></script> A.js, C.js, B.js are executed respectively because "B.js" requires "C.js" that in turn requires "A.js" > The use case was "download several scripts, then execute them all at once". > I'm not sure about that use case, but a prefetch hint doesn't seem right for > that. You'd end up downloading the scripts even if they're never used. There was a use case for fetching a script without ever executing them until execute() is called. I'll argue, however, that UAs should have the option NOT to fetch such a script immediately based on the network condition, bandwidth, etc... That's why I like the name "prefetch" because it implies a weak requirement. Another problem I'm interested in hearing Web developer's opinion is how we can manage the priority of resource requests. e.g. scripts only used for some obscure feature on a page can be requested later; Web browser should be able to prioritize requests for the page's main assets such as the tile image, web fonts, etc... - R. Niwa
