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Re: Should MutationObservers be able to observe work done by the HTML parser?

From: Olli Pettay <Olli.Pettay@helsinki.fi>
Date: Wed, 20 Jun 2012 10:53:32 +0300
Message-ID: <4FE1817C.5010805@helsinki.fi>
To: Ryosuke Niwa <rniwa@webkit.org>
CC: Adam Klein <adamk@chromium.org>, Jonas Sicking <jonas@sicking.cc>, Rafael Weinstein <rafaelw@google.com>, Mihai Parparita <mihaip@chromium.org>, WebApps WG <public-webapps@w3.org>
On 06/20/2012 10:36 AM, Ryosuke Niwa wrote:
> On Tue, Jun 19, 2012 at 1:52 PM, Olli Pettay <Olli.Pettay@helsinki.fi <mailto:Olli.Pettay@helsinki.fi>> wrote:
>
>       Ojan points out
>
>         that simply using end-of-task could expose low-level implementation detail of the parser to script (such as how much parsing is done in a
>         single task
>         before the parser yields).
>
>         Does Firefox do anything special here? Or does it simply use the same end-of-task delivery as everywhere else?
>
>
>     end-of-microtask or end-of-task everywhere. And yes, some parsing / networking details may unfortunately be exposed, but in a way which should be
>     quite random. Web devs just can't really rely on network packages to be delivered to parser in some exact way.
>
>
> That randomness seems undesirable. Can we delay the delivery until DOMContentLoaded is fired so that we can have more consisnte behavior here?

That prevents using MutationObserver for certain cases. Like when you "stream" data using an iframe.

Also, there are already many cases when networking/parsing handling is exposed to the web pages.
Just put any <img onload=".." onerror="...">. When the handlers run, the stuff after the <img> may or may not be in the document.




>
> - Ryosuke
>
Received on Wednesday, 20 June 2012 07:54:17 GMT

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