[webkit-dev] Removing support for CSS regions

Ryosuke Niwa rniwa at webkit.org
Wed Aug 2 00:00:52 PDT 2017

On Tue, Aug 1, 2017 at 11:40 PM, Andreas Kling <akling at apple.com> wrote:
>> On 2 Aug 2017, at 01:03, Ryosuke Niwa <rniwa at webkit.org> wrote:
>> On Mon, Jul 31, 2017 at 1:49 AM, Andreas Kling <akling at apple.com> wrote:
>>> Some time has passed, and it seems that adoption of CSS regions on the web is not gonna happen.
>>> Blink has long since removed their support.
>>> Firefox never supported it AFAIK.
>>> (The new) IE has some amount of support behind a prefix, but no plans to unprefix AFAIK.
>>> I think it’s time we remove the code from WebKit, and relieve ourselves of the maintenance burden.
>>> This should also open up numerous opportunities for clean-up and optimization.
>>> If you know of any reason to keep the feature, such as a major website or WebKit client depending on it, do speak up now!
>> Since we've been shipping CSS regions for a while, I think the first
>> step we should take would be disabling the feature on trunk, and put
>> that into STP and other ports' releases so that we can easily revert
>> the change if we find out any Web content to be broken when the
>> feature is disabled.
>> Unless there is evidence of at least one major site or client depending on CSS regions, I don’t agree that such a slow removal process is necessary.
> IMO doing that would only further increase the maintenance burden incurred by the feature, since we’d have to add tons of runtime checks throughout the codebase.

Given my concern is the compatibility, not the maintenance cost, what
is the evidence that nobody is relying on this feature?

It seems a little crazy to remove a feature that has been available
(prefixed) since Safari 6.2 without any prior warning or gathering any
usage metrics at all.

Also see: https://trac.webkit.org/wiki/DeprecatingFeatures

> I would feel differently if we were pioneering this removal, but since we’ve already seen it succeed in Blink I’m far less concerned.

I'm more concerned about iOS and macOS apps that use WebKit than the
Web content in the wild.

- R. Niwa

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