Intent to implement and ship: forced case-sensitive attribute selector matching

[Boris Zbarsky]

Summary: When matching CSS attribute selectors against HTML, some
attribute names lead to case-sensitive value matching, while others use
ASCII-case-insensitive matching. The proposed feature adds an 's' flag
on attribute selectors that forces case-sensitive matching, just like
the existing 'i' flag forces ASCII-case-insensitive matching.

Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1512386

Standard: https://drafts.csswg.org/selectors-4/#attribute-case

Platform coverage: all

Estimated or target release: Firefox 66.

Preference behind which this will be implemented: None.

Is this feature enabled by default in sandboxed iframes? Yes.

DevTools bug: None needed, as far as I can tell.

Do other browser engines implement this? Not yet. This is a new
addition to the standard.

web-platform-tests: This is tested in the tests in
http://w3c-test.org/css/selectors/attribute-selectors/attribute-case/

Is this feature restricted to secure contexts? No, like other CSS
syntax features.

Spec stability: Not 100% clear, but I expect it's pretty stable; on the
spec level this is a tiny change and there's not much controversy about
which letter to use for the flag, I would think.

Security & Privacy Concerns: None

Web designer / developer use-cases AKA Why a developer would use Feature
X? https://github.com/w3c/csswg-drafts/issues/2101#issue-280846560
describes the main use-case: HTML list styling needs this, because
type="a" and type="A" are different.

Example usage: [foo="bar" s] { color: fuschia }

-Boris

[fantasai]

On 12/11/18 6:34 AM, Boris Zbarsky wrote:
>
> Spec stability: Not 100% clear, but I expect it's pretty stable; on the spec level this is a tiny
change and there's not much controversy about which letter to use for the flag, I would think.

As the editor of the spec, I second this assessment. There are parts
of Selectors 4 that are a little shaky, but this is so closely analogous
to an existing feature that it doesn't seem like one of them.

~fantasai