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Re: Executing script-inserted external scripts in insertion order

From: Henri Sivonen <hsivonen@iki.fi>
Date: Fri, 15 Oct 2010 10:12:51 +0300
Cc: Adam Barth <abarth@webkit.org>, public html <public-html@w3.org>
Message-Id: <D3DC5CCF-75CA-4DA0-9C1E-FA6B28A0F21C@iki.fi>
To: Tony Gentilcore <tonyg@chromium.org>
Tony Gentilcore's reply to public-html bounced, so I'm quoting it here in full with his permission.
On Oct 14, 2010, at 21:35, Tony Gentilcore wrote:

> Re: Changing WebKit to preserve order for script-inserted external scripts.
> In short, I believe that the current WebKit behavior results in the
> best performance for current web content with no known major compat
> problems.
> Expanding on that, my opinion is that developers who don't understand
> the intricacies of script execution order, typically use
> parser-inserted scripts which preserve order by default. In my
> experience working on Google web properties, developers turn to
> script-inserted scripts only when they want a performance gain from
> async behavior. Now we've avoided the need to turn to script-inserted
> scripts to gain async behavior by adding the async attribute to
> parser-inserted scripts, but not many people have migrated to that
> yet. If we were to change the behavior of script-inserted external
> script to preserve the order, I suspect we'd just take a perf hit with
> no concrete compat benefit. That being said, I wouldn't try to stand
> in the way of this change, but I certainly don't want to be the one to
> implement it.
> Re: Prefetching scripts with type=text/cache.
> As of http://trac.webkit.org/changeset/67245, WebKit is in compliance
> with HTML5 and no longer hits the network for scripts it doesn't plan
> to execute. <link rel=prefetch> should be used for prefetching.
> -Tony

Thanks for the reply. Your position on the default is what I feared it would be.

About prefetching: From the changeset you linked to, it seems to me that WebKit trunk is now breaking existing LABjs and RequireJS in their ordered modes. Is <link rel=prefetch> your only current plan for providing a future version of LABjs something to restore functionality with?

Henri Sivonen
Received on Friday, 15 October 2010 07:13:28 UTC

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