[whatwg] Proposal for separating script downloads and execution

Glenn Maynard glenn at zewt.org
Thu May 26 10:33:43 PDT 2011

On Thu, May 26, 2011 at 11:56 AM, Nicholas Zakas <nzakas at yahoo-inc.com> wrote:
> I'm a little surprised that this conversation has swooped back around to performance and whether or not there's a valid use case here.

Stopping and reevaluating periodically is a good idea, when proposing
added complexity to the platform.

> Moving parts of the JavaScript download/execution process doesn't allow me to control when that script will be executed, which as I mentioned in a previous email, is really the crux of the issue.

The crux of the issue, according to your previous mail, was that
executing the top-level of a script has to take a nontrivial amount of
time, which is why you want to control when it happens.  Based on both
benchmarking and logical examination of what's happening, that doesn't
seem to be the case: executing the top-level of a function, when using
the loader-function paradigm, takes no significant time at all.

Can you reply to my mail, and explain why the loader-function paradigm
doesn't work for you?  Maybe we discussed it before, but I'm having
trouble thinking of any problems with it.

> Sorry for repetition, but we can already preload images and CSS and apply them to the page at an arbitrary point in time. Why wouldn't we want the same thing for JavaScript?

You have effectively the same thing with a loader function; it just
takes marginally more cooperation from the resource itself (wrapping
it inside a function), which I think is fine.

Glenn Maynard

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