1761043 - Implement hidden=until-found attribute and beforematch event

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement)

Description

[Joey Arhar]

User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.46 Safari/537.36

Steps to reproduce:

This feature was added to the HTML spec here: https://github.com/whatwg/html/pull/7475
Here is an explainer: https://github.com/WICG/display-locking/blob/main/explainers/hidden-content-explainer.md

The "until-found" value for the hidden attribute should make the element content-visibility:hidden instead of display:none. When the browser searches for text via find-in-page or ScrollToTextFragment, it should also search for text in hidden=until-found elements. If find-in-page or ScrollToTextFragment want to scroll to a match inside a hidden=until-found element, it should remove the hidden attribute from the element and fire the "beforematch" event on it in order to reveal the match.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::DOM: Core & HTML' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Wikipedia uses this attribute now which means find in page works much better in Chrome on Android than in Firefox

Comment 3

[Christian Schaefer]

I've found one more use case where hidden=until-found is very helpful which I described here: https://schepp.dev/posts/rethinking-find-in-page-accessibility-making-hidden-text-work-for-everyone/

I'm aware that this feature is part of Interop 2025 via <details> element, but maybe we can get this quicker than end of this year?

Comment 4

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1761043, part 1 - hidden=until-found: Add pref `dom.hidden_until_found.enabled`. r=emilio!

Comment 5

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1761043, part 2 - hidden=until-found: Implemented webidl changes. r=emilio!

To allow hidden=until-found, the webidl attribute must allow additional data types 0.
Therefore, this patch sets its type to Any,
and implements setter and getter logic that allows
setting the value directly (div.hidden="until-found"
and indirectly (div.setAttribute("hidden", "until-found").

Comment 6

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1761043, part 3 - hidden=until-found: Setting `hidden=until-found` elements as `content-visibility: hidden` instead of `display: none`. r=emilio!

Comment 7

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1761043, part 4 - hidden=until-found: Implement reveal algorithm and the beforematch event. r=emilio!

Comment 8

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1761043, part 5 - hidden=until-found: Implement fragment navigation. r=emilio!

Comment 9

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1761043, part 6 - hidden=until-found: Implemented`hidden=until-found` in `nsFind`. r=emilio!

This fixes Text Fragments tests as well since
that feature relies on nsFind.

Comment 10

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1761043, part 7 - hidden=until-found: Updated some WPTs. r=emilio!

hidden-until-found-002.html needs to use \ue004
instead of \t to work in Gecko.

hidden-ua-stylesheet.html gets additional asserts that
ensure that setting hidden=until-found is set properly
when using setAttribute() with case-insensitive values.

Comment 11

[Daniel Holbert [:dholbert]]

I filed bug 1955379 to enable the pref (the one added in part 1 here) when we're ready, so that we've got that tracked as still needed in order to pass the associated tests on wpt.fyi.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b8e79fffd79a
part 1 - hidden=until-found: Add pref `dom.hidden_until_found.enabled`. r=emilio
https://hg.mozilla.org/integration/autoland/rev/815d42c71c38
part 2 - hidden=until-found: Implemented webidl changes. r=emilio
https://hg.mozilla.org/integration/autoland/rev/e842c0154a9a
part 3 - hidden=until-found: Setting `hidden=until-found` elements as `content-visibility: hidden` instead of `display: none`. r=emilio
https://hg.mozilla.org/integration/autoland/rev/c365b9156d01
part 4 - hidden=until-found: Implement reveal algorithm and the beforematch event. r=emilio
https://hg.mozilla.org/integration/autoland/rev/adc25f3f0b31
part 5 - hidden=until-found: Implement fragment navigation. r=emilio
https://hg.mozilla.org/integration/autoland/rev/8319cbeffeb5
part 6 - hidden=until-found: Implemented`hidden=until-found` in `nsFind`. r=emilio
https://hg.mozilla.org/integration/autoland/rev/6c11ac0d8fda
part 7 - hidden=until-found: Updated some WPTs. r=emilio,smaug

Comment 13

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/51790 for changes under testing/web-platform/tests

Comment 14

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/b8e79fffd79a
https://hg.mozilla.org/mozilla-central/rev/815d42c71c38
https://hg.mozilla.org/mozilla-central/rev/e842c0154a9a
https://hg.mozilla.org/mozilla-central/rev/c365b9156d01
https://hg.mozilla.org/mozilla-central/rev/adc25f3f0b31
https://hg.mozilla.org/mozilla-central/rev/8319cbeffeb5
https://hg.mozilla.org/mozilla-central/rev/6c11ac0d8fda

Comment 15

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot

Comment 16

[Jan Jaeschke [:jjaschke]]

Release Note Request (optional, but appreciated)
[Why is this notable]: hidden=until-found allows content to be found via find-in-page when it's hidden by default. This feature is for example used by the mobile version of Wikipedia.
[Affects Firefox for Android]: Yes
[Suggested wording]:
[Links (documentation, blog post, etc)]: https://github.com/WICG/display-locking/blob/main/explainers/hidden-content-explainer.md

Comment 17

[Jan Jaeschke [:jjaschke]]

(duplicate comment)

Comment 18

[Ryan VanderMeulen [:RyanVM]]

Added to the nightly relnotes.

Comment 19

[Donal Meehan [:dmeehan]]

Removing from the Nightly release notes for Fx140+
This was enabled by default for Fx139 under Bug 1955379

Comment 20

[Brian Thomas Smith [bsmth]]

MDN changes for this (and the pref 'dom.hidden_until_found.enabled' bug https://bugzilla.mozilla.org/show_bug.cgi?id=1955379) can be tracked in the following GitHub issue: https://github.com/mdn/content/issues/39306