*Summary:* Scoped Custom Element Registries allow multiple custom element registries per page, meaning each sub-tree can define a how custom elements are defined and upgraded. This feature shipped in Safari 26 and Chrome 146, and is part of the Interop 2026 project. We've been prototyping the feature under the `dom.scoped-custom-element-registries.enabled` flag, which is currently enabled in Nightly builds.
During prototyping this feature, we identified some issues related to how custom elements integrate with the Sanitizer API. Therefore the "Sanitize While Parsing" feature has also been prototyped, as this is an effective prerequisite for Scoped Registries. I have just submitted an intent to ship that feature (https://groups.google.com/a/mozilla.org/g/dev-platform/c/pBp2LDM2vqI/m/nHobL64xBAAJ) which will allow us to ship Scoped Registries. Scoped Registries can be safely shipped with the "Sanitize While Parsing" feature. Once the *159* release cycle has started (September 24) I intend to turn this feature (scoped registries) on by default on all platforms, meaning it will (barring any major issues) ship by default in 159 (October 27). If there are issues in the "Sanitize While Parsing" feature that require a rollback, I will also roll back the Scoped Registries feature. As usual, if any other issues arise, please let me know and I will happily roll the flag back. Happy (scoped) browsing! *Bug to turn on by default:* https://bugzilla.mozilla.org/show_bug.cgi?id=2070506 *Standard:* https://html.spec.whatwg.org/multipage/custom-elements.html#customelementregistry *Intent to Prototype Thread:* This feature was previously discussed in this "Intent to Prototype" thread: https://groups.google.com/a/mozilla.org/g/dev-platform/c/4UoaI67Awcg/m/49uzaQJTCgAJ, the tracking bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1874414. *TAG Review:* N/A -- You received this message because you are subscribed to the Google Groups "[email protected]" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/mozilla.org/d/msgid/dev-platform/4d7993d8-e588-44e2-a8a4-516bf474431a%40app.fastmail.com.
