Intent to Prototype: Shadow root clonable attribute

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Mason Freed

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Jan 26, 2024, 3:53:16 PMJan 26

to blink-dev

Contact emails

mas...@chromium.org

Explainer

None

Specification

https://dom.spec.whatwg.org/#shadowroot-clonable

Summary

This enables individual control over whether a shadow root is clonable (via standard platform cloning commands such as `cloneNode()`). By default, declarative shadow roots are clonable. Imperative shadow roots can now be controlled via a parameter to `attachShadow()`.

Blink component

Blink>DOM>ShadowDOM

Motivation

None

Initial public proposal

None

Search tags

declarative shadow dom

TAG review

None

TAG review status

Not applicable

Risks

Interoperability and Compatibility

This is a slight change in behavior, which poses a very small compat risk. Prior to this feature, only declarative shadow roots within `<template>` elements would get automatically cloned. With the change, any declarative shadow root, even in the main page, will get cloned. Safari already shipped the new behavior, reducing the risk. I plan to enable this functionality slowly and monitor for breakage and bug reports.

Gecko: Positive (https://bugzilla.mozilla.org/show_bug.cgi?id=1868428) Shipping soon

WebKit: Shipped/Shipping (https://developer.apple.com/documentation/safari-release-notes/safari-17_4-release-notes#Web-API)

Web developers: No signals

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