[webkit-dev] CSSOM View behavior for scrollLeft, scrollTop, scrollWidth etc

Frédéric Wang fwang at igalia.com
Mon Sep 10 01:41:38 PDT 2018

Hi all,

The new behavior is enabled for tests after
Essentially, this means that if you want set/get the scroll position of
the test pages, you should now just use document.scrollingElement
instead of document.body.

I'll wait a few days before proposing to set it to


On 30/01/2018 17:21, Frédéric Wang wrote:
> Hi everybody,
> I'd like to announce that I started to implement the behavior for
> scrollLeft, scrollTop, scrollWidth, scrollHeight, scrollTo, scrollBy and
> scrollingElement [1] as specified by the CSSOM View specification [2].
> To summarize, the main difference is which element to use in order to
> set or get the scroll properties of the viewport in standard
> (non-Quirks) mode:
> * The CSSOM View spec says it should be document.documentElement and
> most browsers implement it that way.
> * Chromium used to use document.body but this has recently been changed
> to follow the CSSOM View spec [3].
> * WebKit still uses document.body and I'm proposing to change this behavior.
> Note that this is likely to break existing content. The change was
> attempted in WebKit in the past but broke some non-regression tests [4].
> Chromium people also had some issues when trying to ship the change but
> things went well at the end [5].
> For now I'm developing it under a CSSOMViewScrollingAPI developer flag.
> I was able to run the tests with that flag enabled, modulo a few test
> adjustments.
> [1] https://bugs.webkit.org/show_bug.cgi?id=5991
> [2] https://drafts.csswg.org/cssom-view
> [3]
> https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/X64Sg16RhT4
> [4] https://bugs.webkit.org/show_bug.cgi?id=106133,
> https://bugs.webkit.org/show_bug.cgi?id=121876
> [5]
> https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/2iOz5-fgD8Y/GO7qLkg4BwAJ
> ; https://bugs.webkit.org/show_bug.cgi?id=5991#c20

Frédéric Wang - frederic-wang.fr

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