Add Scoped Custom Element Registries #1341

annevk · 2024-12-17T17:30:55Z

Please do not comment directly on this PR unless asked. It's a big change and we want to keep it manageable. Use #1339 instead.

HTML PR: whatwg/html#10869.

Tests: web-platform-tests/wpt#50790.

At least two implementers are interested (and none opposed):
- WebKit
- …
Tests are written and can be reviewed and commented upon at:
- Export WebKit's tests for revamped scoped custom element registry. web-platform-tests/wpt#50790
- DOM: rename importNode()'s deep to selfOnly (and invert its value) web-platform-tests/wpt#50860
- TODO: PR to make them non-tentative
Implementation bugs are filed:
- Chromium: https://issues.chromium.org/issues/399124619
- Gecko: https://bugzilla.mozilla.org/show_bug.cgi?id=1874414
- WebKit: N/A
MDN issue is filed: Scoped Custom Element Registries mdn/content#38266
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Do not comment directly on this PR while it is in draft state. Use #10854 instead. DOM PR: whatwg/dom#1341. Tests: ...

DOM PR: whatwg/dom#1341. Tests: ... Closes #10854.

HTML PR: whatwg/html#10869. Tests: ... Closes #1339.

DOM PR: whatwg/dom#1341. Tests: ... Closes #10854.

Part of whatwg/dom#1341.

For whatwg/dom#1341.

…nly (and invert its value), a=testonly Automatic update from web-platform-tests DOM: rename importNode()'s deep to selfOnly (and invert its value) Part of whatwg/dom#1341. -- wpt-commits: 5bcf44cb07a74e284893af96926d932ec09705e7 wpt-pr: 50860

…ith scoped registries, a=testonly Automatic update from web-platform-tests DOM: createElement and createElementNS with scoped registries For whatwg/dom#1341. -- wpt-commits: a52f97983743aae5fdd5172c9938b47743dc7146 wpt-pr: 50925

…nly (and invert its value), a=testonly Automatic update from web-platform-tests DOM: rename importNode()'s deep to selfOnly (and invert its value) Part of whatwg/dom#1341. -- wpt-commits: 5bcf44cb07a74e284893af96926d932ec09705e7 wpt-pr: 50860

…ith scoped registries, a=testonly Automatic update from web-platform-tests DOM: createElement and createElementNS with scoped registries For whatwg/dom#1341. -- wpt-commits: a52f97983743aae5fdd5172c9938b47743dc7146 wpt-pr: 50925

…nly (and invert its value), a=testonly Automatic update from web-platform-tests DOM: rename importNode()'s deep to selfOnly (and invert its value) Part of whatwg/dom#1341. -- wpt-commits: 5bcf44cb07a74e284893af96926d932ec09705e7 wpt-pr: 50860 UltraBlame original commit: 4a4c1689ebd912108057f71fa24393009d4ab18a

…ith scoped registries, a=testonly Automatic update from web-platform-tests DOM: createElement and createElementNS with scoped registries For whatwg/dom#1341. -- wpt-commits: a52f97983743aae5fdd5172c9938b47743dc7146 wpt-pr: 50925 UltraBlame original commit: 78ef3074b0082c9e95d840a8010b34661973a847

…nly (and invert its value), a=testonly Automatic update from web-platform-tests DOM: rename importNode()'s deep to selfOnly (and invert its value) Part of whatwg/dom#1341. -- wpt-commits: 5bcf44cb07a74e284893af96926d932ec09705e7 wpt-pr: 50860 UltraBlame original commit: 4a4c1689ebd912108057f71fa24393009d4ab18a

…ith scoped registries, a=testonly Automatic update from web-platform-tests DOM: createElement and createElementNS with scoped registries For whatwg/dom#1341. -- wpt-commits: a52f97983743aae5fdd5172c9938b47743dc7146 wpt-pr: 50925 UltraBlame original commit: 78ef3074b0082c9e95d840a8010b34661973a847

…nly (and invert its value), a=testonly Automatic update from web-platform-tests DOM: rename importNode()'s deep to selfOnly (and invert its value) Part of whatwg/dom#1341. -- wpt-commits: 5bcf44cb07a74e284893af96926d932ec09705e7 wpt-pr: 50860 UltraBlame original commit: 4a4c1689ebd912108057f71fa24393009d4ab18a

…ith scoped registries, a=testonly Automatic update from web-platform-tests DOM: createElement and createElementNS with scoped registries For whatwg/dom#1341. -- wpt-commits: a52f97983743aae5fdd5172c9938b47743dc7146 wpt-pr: 50925 UltraBlame original commit: 78ef3074b0082c9e95d840a8010b34661973a847

…nly (and invert its value), a=testonly Automatic update from web-platform-tests DOM: rename importNode()'s deep to selfOnly (and invert its value) Part of whatwg/dom#1341. -- wpt-commits: 5bcf44cb07a74e284893af96926d932ec09705e7 wpt-pr: 50860

…ith scoped registries, a=testonly Automatic update from web-platform-tests DOM: createElement and createElementNS with scoped registries For whatwg/dom#1341. -- wpt-commits: a52f97983743aae5fdd5172c9938b47743dc7146 wpt-pr: 50925

DOM PR: whatwg/dom#1341. Tests: ... Closes #10854.

justinfagnani · 2025-03-18T22:24:12Z

dom.bs

+ otherwise null.
+</dl>
+
+<p>The <dfn attribute for=DocumentOrShadowRoot><code>customElementRegistry</code></dfn> getter steps


Are there setter steps for shadow roots with keep custom element registry null set to true?

No, you have to use the initialize() API.

justinfagnani · 2025-03-18T22:36:16Z

dom.bs

+<p><a for=/>Shadow roots</a> have an associated
+<dfn for=ShadowRoot>keep custom element registry null</dfn> (a boolean). It is initially false.
+
+<p class=note>This can only ever be true in combination with declarative shadow roots. And it only


Are there any cases where we want to be able to programmatically create shadow roots that emulate declarative shadow roots with a null registry?

I think this might be the first instance where we can't imperatively make a shadow root that matches a declarative shadow root. That should be an issue for polyfilling (true polyfills after some browsers have shipped) things for DSD.

For instance, to polyfill this feature, we would need to prevent declarative shadow roots from using the global registry. So we would have to emit on the server templates with an alternate shadowrootmode attribute, and imperatively instantiate the shadow roots, and record the fact that it had shadowrootcustomelementregistry attribute.

If a future feature required a similar technique, then either we'd need to be able to set this option when creating the shadow root or be able to set a shadow root's registry to null.

You already can't create all declarative shadow roots. Only declarative shadow roots have the declarative bit set, for instance.

annevk added a commit to whatwg/html that referenced this pull request Dec 17, 2024

Add Scoped Custom Element Registries

9aecb05

Do not comment directly on this PR while it is in draft state. Use #10854 instead. DOM PR: whatwg/dom#1341. Tests: ...

This was referenced Dec 17, 2024

Add Scoped Custom Element Registries whatwg/html#10869

Open

Revamped Scoped Custom Element Registries whatwg/html#10854

Open

annevk marked this pull request as ready for review December 19, 2024 09:51

annevk added topic: custom elements Relates to custom elements (as defined in DOM and HTML) addition/proposal New features or enhancements topic: shadow Relates to shadow trees (as defined in DOM) topic: nodes labels Dec 19, 2024

annevk force-pushed the annevk/scoped-custom-element-registries branch from 66f3a02 to dacf095 Compare December 19, 2024 10:05

annevk added a commit to whatwg/html that referenced this pull request Dec 19, 2024

Add Scoped Custom Element Registries

3ad2431

DOM PR: whatwg/dom#1341. Tests: ... Closes #10854.

annevk added 2 commits February 21, 2025 10:40

Add Scoped Custom Element Registries

9137b50

HTML PR: whatwg/html#10869. Tests: ... Closes #1339.

Fix createElement and importNode

7e04bae

annevk force-pushed the annevk/scoped-custom-element-registries branch from dacf095 to 7e04bae Compare February 21, 2025 09:40

annevk added a commit to whatwg/html that referenced this pull request Feb 21, 2025

Add Scoped Custom Element Registries

2a6fa8f

DOM PR: whatwg/dom#1341. Tests: ... Closes #10854.

annevk added 2 commits February 21, 2025 10:44

CI

f441601

CI again

71537d2

annevk mentioned this pull request Feb 21, 2025

Scoped Custom Element Registries mdn/content#38266

Open

annevk added a commit to web-platform-tests/wpt that referenced this pull request Feb 21, 2025

DOM: rename importNode()'s deep to selfOnly (and invert its value)

666cc13

Part of whatwg/dom#1341.

annevk mentioned this pull request Feb 21, 2025

DOM: rename importNode()'s deep to selfOnly (and invert its value) web-platform-tests/wpt#50860

Merged

annevk added a commit to web-platform-tests/wpt that referenced this pull request Feb 22, 2025

DOM: rename importNode()'s deep to selfOnly (and invert its value)

5bcf44c

Part of whatwg/dom#1341.

rniwa mentioned this pull request Feb 25, 2025

Sessions for March 26th W3C Breakout Day 2025 WICG/webcomponents#1095

Open

annevk added a commit to web-platform-tests/wpt that referenced this pull request Feb 25, 2025

DOM: createElement and createElementNS with scoped registries

197e5ea

For whatwg/dom#1341.

annevk mentioned this pull request Feb 25, 2025

DOM: createElement and createElementNS with scoped registries web-platform-tests/wpt#50925

Merged

annevk added a commit to web-platform-tests/wpt that referenced this pull request Feb 25, 2025

DOM: createElement and createElementNS with scoped registries

a52f979

For whatwg/dom#1341.

Do not make registries cross the shadow boundary

2038a33

annevk linked an issue Feb 26, 2025 that may be closed by this pull request

Revamped Scoped Custom Element Registries (DOM side) #1339

Open

Nice one CI

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annevk linked an issue Feb 26, 2025 that may be closed by this pull request

Revamped Scoped Custom Element Registries whatwg/html#10854

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4 tasks

Account for polyfill nonsense

da94abc

annevk mentioned this pull request Mar 3, 2025

Web Compatibility of Scoped Custom Element Registries whatwg/html#11076

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annevk added a commit to whatwg/html that referenced this pull request Mar 6, 2025

Add Scoped Custom Element Registries

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DOM PR: whatwg/dom#1341. Tests: ... Closes #10854.

Polyfill rename, expose document.customElementRegistry

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rniwa mentioned this pull request Mar 17, 2025

Scoped custom element registry w3c/breakouts-day-2025#18

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keithamus mentioned this pull request Mar 18, 2025

Scoped Custom Element Registries w3ctag/design-reviews#1070

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Add Scoped Custom Element Registries #1341

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