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[Bug 11295] Make script-inserted external scripts that have .async=false execute in the insertion order, default to true

From: <bugzilla@jessica.w3.org>
Date: Sat, 08 Jan 2011 07:09:38 +0000
To: public-html-bugzilla@w3.org
Message-Id: <E1PbSvi-0000lf-9H@jessica.w3.org>

--- Comment #15 from Kyle Simpson <w3c@getify.myspamkiller.com> 2011-01-08 07:09:37 UTC ---
(in reply to comment #14)

I still strongly feel the proposal for the symmetry of "async=false" has value
in most of the use-cases surrounding script loading. I am very glad and
thankful that Ian has considered spec'ing the simple proposal.

The majority of sites do NOT have such a complex dependency graph of multiple
independent trees of dependencies, in which the single "global queue" you refer
to would become any kind of a bottleneck or hindrance.

That's not to say that type of use-case is invalid. Sites like that certainly
exist, and there's value to a mechanism that could address that use-case, very
well perhaps using the "preloading" mechanism you referred to, which is
currently specified as a "may" option for browser vendors (in step 12 of the
script loading algorithm). 

In fact, if combined with something like `readyState` monitoring (like IE's
implementation does), there's a very valuable set of advanced use-cases for
loading scripts but deferring (some or all of) their execution until much
later. This is functionality we should definitely ask browser vendors to
implement (as it's already suggested in the spec). 

Granted, the "preloading" mechanism IS functionality that would not only fully
serve, but also exceed, the capabilities of the currently discussed
"async=false" proposal.

HOWEVER, I think it's a mistake to conflate these two different sets of
functionality into one discussion, or to suggest that one precludes the utility
of the other. I think they're separate, and should be kept that way, and that
each of them has independent merit.

The value to the currently discussed "async=false", on top of the
consistency/symmetry argument (which is strong in and of itself), is that it
serves a pretty sizeable chunk of the web's current needs for script loading,
and does so in a way that is very simple and straightforward for script loaders
to utilize. If say 80% of all sites' script loading needs can be well-served by
"async=false" (a relatively simple change for most browsers), then I think it
has value (instead of a more complex system that might also work).

In a separate (but certainly useful) effort, I think the more advanced 20%
use-cases (more complex dependency trees) can and should be pushed via the
other "preloading" mechanism (aka, load-but-don't-execute). However, *that*
discussion doesn't really belong here (since the spec already mentions both its
method and value), but rather with browser vendors directly.

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Received on Saturday, 8 January 2011 07:09:39 UTC

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