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Re: Shadow DOM: state of the distribution API

From: Hayato Ito <hayato@chromium.org>
Date: Thu, 07 May 2015 06:22:03 +0000
Message-ID: <CAFpjS_3vDruF4eEopJyRHvc1_nmas_CtGbHneC2u12P0PyHbfQ@mail.gmail.com>
To: Ryosuke Niwa <rniwa@apple.com>, Elliott Sprehn <esprehn@chromium.org>
Cc: Jonas Sicking <jonas@sicking.cc>, Anne van Kesteren <annevk@annevk.nl>, WebApps WG <public-webapps@w3.org>
I'm happy to implement some of these proposals in blink to compare the
performance when the time comes, if I or other guys can afford to do.

On Thu, May 7, 2015 at 1:20 PM Hayato Ito <hayato@chromium.org> wrote:

> I'm wondering how we should estimate the performance impact of these
> proposals.
> In the era of Web Components, I expect that one page has 1k Web
> Components. The page must work without any significant noticeable
> performance regression, compared to a page which doesn't use Web
> Components. That's our bottom line.
> In the current distribution model, I expect we can achieve this goal,
> thanks to the lazy evaluation of distribution.
> Is there any plan how we should evaluate these proposals in terms of
> performance primitives?
> On Thu, May 7, 2015 at 7:53 AM Ryosuke Niwa <rniwa@apple.com> wrote:
>> > On May 6, 2015, at 2:39 PM, Elliott Sprehn <esprehn@chromium.org>
>> wrote:
>> >
>> > The 3 proposal is what the houdini effort is already researching for
>> custom style/layout/paint. I don't think it's acceptable to make all usage
>> of Shadow DOM break when used with libraries that read layout information
>> today, ie. offsetTop must work. I also don't think it's acceptable to
>> introduce new synchronous hooks and promote n^2 churn in the distribution.
>> Sorry, I don't follow. If we're making offsetTop to synchronously return
>> the correct value, then authors can easily write code that performs in
>> Ω(n^2) by obtaining the value of offsetTop between adding/removing direct
>> children of a shadow host.  On the other hand, if we're trying to prevent
>> O(n^2) behavior, then we should be adding API to asynchronously retrieve
>> layout information.
>> - R. Niwa
Received on Thursday, 7 May 2015 06:22:32 UTC

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