Add declarative Shadow DOM features #892

mfreed7 · 2020-09-15T21:17:06Z

The explainer for this feature is here: https://github.com/mfreed7/declarative-shadow-dom/blob/master/README.md
The issue discussion is here: #831
There is a corresponding Pull Request for the HTML spec that goes along with this PR.

Note, due to some local branch issues, this is a duplicate of PR 858. Please see that PR for more history and review comments here. In particular, the last comment there is from me - it is my belief that I've addressed all of the outstanding comments.

At least two implementers are interested (and none opposed):
- I'm working to get this implemented in Chromium, tracking bug here.
- Other implementers have at least not been negative on the discussion thread. Not explicitly positive (yet).
Tests are written and can be reviewed and commented upon at:
- https://wpt.fyi/results/shadow-dom/declarative?label=master&label=experimental&aligned&q=declarative
Implementation bugs are filed:
- Chrome: https://crbug.com/1042130
- Firefox: None yet
- Safari: None yet

Closes #1137.

Preview | Diff

This CL implements most of the suggestions from [1], which effectively block declarative Shadow DOM from being used by any fragment parser entry point, unless an explicit opt-in is toggled. The opt-ins include: - DOMParser.allowDeclarativeShadowDom = true; - HTMLTemplateElement.allowDeclarativeShadowDom = true; - XMLHttpRequest.allowDeclarativeShadowDom = true; - DocumentFragment.allowDeclarativeShadowDom = true; - Document.allowDeclarativeShadowDom = true; // For innerHTML - A new <iframe> sandbox flag: allow-declarative-shadow-dom This mitigates the potential client-side XSS sanitizer bypass detailed in the explainer and at [1]. Assuming these changes are functional, and mitigate the issue, this new behavior will be folded into the spec PRs at [2] and [3]. But given the security implications of the existing code, I'd like to get this landed first. [1] whatwg/dom#912 (comment) [2] whatwg/html#5465 [3] whatwg/dom#892 Bug: 1042130 Change-Id: I088f28f63078a0d26e354a4442494c0132b47ffc

This CL implements most of the suggestions from [1], which effectively block declarative Shadow DOM from being used by any fragment parser entry point, unless an explicit opt-in is toggled. The opt-ins include: - DOMParser.allowDeclarativeShadowDom = true; - HTMLTemplateElement.allowDeclarativeShadowDom = true; - XMLHttpRequest.allowDeclarativeShadowDom = true; - DocumentFragment.allowDeclarativeShadowDom = true; - Document.allowDeclarativeShadowDom = true; // For innerHTML - A new <iframe> sandbox flag: allow-declarative-shadow-dom This mitigates the potential client-side XSS sanitizer bypass detailed in the explainer and at [1]. Assuming these changes are functional, and mitigate the issue, this new behavior will be folded into the spec PRs at [2] and [3]. But given the security implications of the existing code, I'd like to get this landed first. [1] whatwg/dom#912 (comment) [2] whatwg/html#5465 [3] whatwg/dom#892 Bug: 1042130 Change-Id: I088f28f63078a0d26e354a4442494c0132b47ffc Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2513525 Commit-Queue: Mason Freed <masonfreed@chromium.org> Reviewed-by: Kouhei Ueno <kouhei@chromium.org> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org> Cr-Commit-Position: refs/heads/master@{#824591}

…arsing to be opt-in, a=testonly Automatic update from web-platform-tests Change declarative Shadow DOM fragment parsing to be opt-in This CL implements most of the suggestions from [1], which effectively block declarative Shadow DOM from being used by any fragment parser entry point, unless an explicit opt-in is toggled. The opt-ins include: - DOMParser.allowDeclarativeShadowDom = true; - HTMLTemplateElement.allowDeclarativeShadowDom = true; - XMLHttpRequest.allowDeclarativeShadowDom = true; - DocumentFragment.allowDeclarativeShadowDom = true; - Document.allowDeclarativeShadowDom = true; // For innerHTML - A new <iframe> sandbox flag: allow-declarative-shadow-dom This mitigates the potential client-side XSS sanitizer bypass detailed in the explainer and at [1]. Assuming these changes are functional, and mitigate the issue, this new behavior will be folded into the spec PRs at [2] and [3]. But given the security implications of the existing code, I'd like to get this landed first. [1] whatwg/dom#912 (comment) [2] whatwg/html#5465 [3] whatwg/dom#892 Bug: 1042130 Change-Id: I088f28f63078a0d26e354a4442494c0132b47ffc Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2513525 Commit-Queue: Mason Freed <masonfreed@chromium.org> Reviewed-by: Kouhei Ueno <kouhei@chromium.org> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org> Cr-Commit-Position: refs/heads/master@{#824591} -- wpt-commits: b13461b9a46b46eb1b092a58bde2b10418e7a73d wpt-pr: 26398

mfreed7 · 2020-11-24T18:35:55Z

This PR has been updated to include the "opt-in" mechanics described in #912. The changes I made here roughly match the current implementation of Chromium, so I'm hoping they're functional. But comments appreciated.

Here, I am unable to figure out how to get the "magic" {{include shadow roots state}} to link over to the equivalent section of HTML. I get a build error there. I cannot find where in dom.bs these strings are defined.

dom.bs

annevk · 2020-12-03T15:26:07Z

As for the build error, once HTML is indexed by Shepherd you should be able to cross-reference, but that does mean broken builds until that happens unfortunately. We don't have a good workaround. (One of the nice things about Bikeshed is that it doesn't need a full local index of terms defined elsewhere.)

mfreed7 · 2020-12-04T01:23:30Z

As for the build error, once HTML is indexed by Shepherd you should be able to cross-reference, but that does mean broken builds until that happens unfortunately. We don't have a good workaround. (One of the nice things about Bikeshed is that it doesn't need a full local index of terms defined elsewhere.)

Ahh ok, that makes sense. Thanks.

dom.bs

vekunz · 2022-02-14T14:49:13Z

Is there still progress here or is the topic dead?

mfreed7 · 2022-03-26T01:32:26Z

Is there still progress here or is the topic dead?

This feature is fully shipped on chromium browsers. The other implementers are waiting for production performance data, to help convince them that SSR (and DSD) offers actual performance benefits on real sites. That’s despite recent blog posts that seem to have a different view:

We also continue to see room for improving or adding primitives that provide declarative alternatives for situations that currently require JavaScript, such as…

This feature is not dead.

annevk · 2022-04-04T12:46:17Z

@mfreed7 I think that's a mischaracterization of Mozilla's views and seems somewhat unwarranted? We've been plenty supportive of exploring declarative web components. We're just not quite convinced of declarative shadow trees in isolation.

mfreed7 · 2022-04-05T14:20:01Z

@mfreed7 I think that's a mischaracterization of Mozilla's views and seems somewhat unwarranted? We've been plenty supportive of exploring declarative web components. We're just not quite convinced of declarative shadow trees in isolation.

I’m sorry you feel that way! I honestly didn’t mean to mischaracterize anything. (The link to your blog post might not have been fair, I suppose, though it is a very public blog post.) But I’ve been working for ~a year trying to gather production performance data on this feature precisely because I thought this was Mozilla’s view. E.g. see the latest comment from @smaug---- on the issue thread, which is talking about performance concerns related to (declarative/all) shadow roots. Since declarative custom elements (which are vaporware at this point) would almost surely build on top of declarative shadow dom, I would think those concerns are shared, no?

mfreed7 · 2023-10-04T20:14:23Z

This needed rebasing due to #1200.

Gah, sorry! I read the above comment as "This needs rebasing..." so I just went for it. I didn't notice that you also pushed some things to my branch. Glad you got it back - thanks. And sorry for the trouble.

mfreed7 · 2023-10-04T20:18:50Z

Wait what? Shit. I did the work to rebase. Your subsequent force push overwrote a number of fixes: https://github.com/whatwg/dom/compare/17ede93b019cb319c9b786dfce950c2ba17ec3c3..f01b44dd4d6e88d39216a36c4cb47d58125301d2.

All of these changes look good, much appreciated.

A longer explanation of this feature can be found at https://github.com/mfreed7/declarative-shadow-dom/blob/master/README.md. It was originally discussed in whatwg/dom#831. Corresponding DOM PR: whatwg/dom#892. Tests: shadow-dom/declarative in WPT with web-platform-tests/wpt#42833 being the latest PR as of this commit. Closes #7069.

This landed in the latest declarative shadow dom spec PR: whatwg/dom#892 and was discussed here: whatwg/dom#1137 This CL adds support for that, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Fixed: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728

This landed in the latest declarative shadow dom spec PR: whatwg/dom#892 and was discussed here: whatwg/dom#1137 This CL adds support for that, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Fixed: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728

This landed in the these two spec PRs: whatwg/dom#892 whatwg/dom#1237 and was discussed here: whatwg/dom#1137 whatwg/dom#1236 This CL adds support for clonable, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Fixed: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728

This landed in the these two spec PRs: whatwg/dom#892 whatwg/dom#1237 and was discussed here: whatwg/dom#1137 whatwg/dom#1236 This CL adds support for clonable, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Chromestatus: https://chromestatus.com/feature/5161435196030976 I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/nZhPt0ePCAA Fixed: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728

This landed in the these two spec PRs: whatwg/dom#892 whatwg/dom#1237 and was discussed here: whatwg/dom#1137 whatwg/dom#1236 This CL adds support for clonable, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Chromestatus: https://chromestatus.com/feature/5161435196030976 I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/nZhPt0ePCAA Bug: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728

This landed in the these two spec PRs: whatwg/dom#892 whatwg/dom#1237 and was discussed here: whatwg/dom#1137 whatwg/dom#1236 This CL adds support for clonable, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Chromestatus: https://chromestatus.com/feature/5161435196030976 I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/nZhPt0ePCAA Bug: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5239277 Auto-Submit: Mason Freed <masonf@chromium.org> Reviewed-by: David Baron <dbaron@chromium.org> Commit-Queue: David Baron <dbaron@chromium.org> Cr-Commit-Position: refs/heads/main@{#1253059}

… flag, a=testonly Automatic update from web-platform-tests Add support for the shadow root clonable flag This landed in the these two spec PRs: whatwg/dom#892 whatwg/dom#1237 and was discussed here: whatwg/dom#1137 whatwg/dom#1236 This CL adds support for clonable, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Chromestatus: https://chromestatus.com/feature/5161435196030976 I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/nZhPt0ePCAA Bug: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5239277 Auto-Submit: Mason Freed <masonf@chromium.org> Reviewed-by: David Baron <dbaron@chromium.org> Commit-Queue: David Baron <dbaron@chromium.org> Cr-Commit-Position: refs/heads/main@{#1253059} -- wpt-commits: adc1ac02e6d8e080508325ab4525bab8d09177a6 wpt-pr: 44216

… flag, a=testonly Automatic update from web-platform-tests Add support for the shadow root clonable flag This landed in the these two spec PRs: whatwg/dom#892 whatwg/dom#1237 and was discussed here: whatwg/dom#1137 whatwg/dom#1236 This CL adds support for clonable, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Chromestatus: https://chromestatus.com/feature/5161435196030976 I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/nZhPt0ePCAA Bug: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5239277 Auto-Submit: Mason Freed <masonfchromium.org> Reviewed-by: David Baron <dbaronchromium.org> Commit-Queue: David Baron <dbaronchromium.org> Cr-Commit-Position: refs/heads/main{#1253059} -- wpt-commits: adc1ac02e6d8e080508325ab4525bab8d09177a6 wpt-pr: 44216 UltraBlame original commit: c628961696861f1ee92fe22401f9f939d8df6a8d

This landed in the these two spec PRs: whatwg/dom#892 whatwg/dom#1237 and was discussed here: whatwg/dom#1137 whatwg/dom#1236 This CL adds support for clonable, behind a new ShadowRootClonable flag. There was already a very basic test, but I added a few more cases. This should be fairly web compatible, but there is a risk since with this feature enabled, declarative shadow roots in the main document (as opposed to in a <template> element) will now be cloned. I will launch this feature carefully. Safari has already shipped, and Gecko has implemented this and plans to ship soon. Chromestatus: https://chromestatus.com/feature/5161435196030976 I2P: https://groups.google.com/a/chromium.org/g/blink-dev/c/nZhPt0ePCAA Bug: 1510466 Change-Id: Ie25b72f369ca0542555f91010b0f22d295403728 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5239277 Auto-Submit: Mason Freed <masonf@chromium.org> Reviewed-by: David Baron <dbaron@chromium.org> Commit-Queue: David Baron <dbaron@chromium.org> Cr-Commit-Position: refs/heads/main@{#1253059}

This was referenced Sep 15, 2020

Add declarative Shadow DOM features #858

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Add declarative Shadow DOM features whatwg/html#5465

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mfreed7 mentioned this pull request Oct 5, 2020

Declarative Shadow DOM #831

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mfreed7 force-pushed the add_declarative branch from 26a587c to efafdc6 Compare October 14, 2020 18:22

chromium-wpt-export-bot mentioned this pull request Nov 4, 2020

Change declarative Shadow DOM fragment parsing to be opt-in web-platform-tests/wpt#26398

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mfreed7 mentioned this pull request Nov 16, 2020

[Declarative Shadow DOM] How should we build the "opt-in" for fragment parsing of declarative Shadow DOM? #912

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mfreed7 force-pushed the add_declarative branch from efafdc6 to 968ae19 Compare November 24, 2020 18:25

mfreed7 mentioned this pull request Nov 24, 2020

Add link to declarative shadow dom opt-in whatwg/xhr#300

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annevk reviewed Dec 3, 2020

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mfreed7 mentioned this pull request Feb 18, 2021

Declarative Shadow DOM mozilla/standards-positions#335

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mfreed7 mentioned this pull request Mar 29, 2021

getInnerHTML shouldn't distinguish between open and closed mfreed7/declarative-shadow-dom#9

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rniwa mentioned this pull request Apr 25, 2021

Instead of assignable FrozenArray, use add / remove WICG/construct-stylesheets#45

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mfreed7 mentioned this pull request Sep 11, 2021

Define speculative HTML parsing whatwg/html#5959

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zcorpan mentioned this pull request Sep 14, 2021

Allow speculative fetches in Declarative Shadow DOM template elements whatwg/html#7069

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annevk approved these changes Oct 29, 2023

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annevk merged commit ca756e0 into whatwg:main Oct 29, 2023
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annevk added topic: nodes topic: shadow Relates to shadow trees (as defined in DOM) and removed do not merge yet Pull request must not be merged per rationale in comment labels Oct 29, 2023

saschanaz mentioned this pull request Nov 26, 2023

Corresponding attribute for clonable of ShadowRootInit? #1236

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chromium-wpt-export-bot mentioned this pull request Jan 26, 2024

Add support for the shadow root clonable flag web-platform-tests/wpt#44216

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dandclark mentioned this pull request Apr 3, 2024

Restore missing word in attach a shadow root #1273

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Add declarative Shadow DOM features #892

Add declarative Shadow DOM features #892

mfreed7 commented Sep 15, 2020 •

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Add declarative Shadow DOM features #892

Add declarative Shadow DOM features #892

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