Contact emailsmas...@chromium.org ExplainerNone
Specificationhttps://w3c.github.io/uievents/#legacy-event-types Summary Synchronous Mutation Events, including `DOMSubtreeModified`, `DOMNodeInserted`, `DOMNodeRemoved`, `DOMNodeRemovedFromDocument`, `DOMNodeInsertedIntoDocument`, and `DOMCharacterDataModified`, are quite bad for page performance, and also significantly increase the complexity of adding new features to the Web. These APIs were deprecated from the spec ( https://w3c.github.io/uievents/#legacy-event-types) in 2011, and were replaced (in 2012) by the much better-behaved Mutation Observer API. Usage of the obsolete Mutation Events must be migrated to Mutation Observer. Blink componentBlink>DOM <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EDOM> Motivation Mutation Events have been deprecated for over a decade, with the replacement (Mutation Observer) available also for over a decade. The fact that these events are still supported in browsers makes the addition of new features much more difficult, prohibitively so in some cases. For example, these feature requests and projects are all negatively impacted by the existence of Mutation Events: - iFrame reparenting: https://github.com/whatwg/html/issues/5484 and https://github.com/whatwg/dom/issues/891 - Child reordering: https://github.com/whatwg/dom/issues/586 - DOM Parts and batch DOM updates: https://github.com/WICG/webcomponents/blob/gh-pages/proposals/DOM-Parts.md Given that the feature has been spec-deprecated for a decade, it makes sense to officially deprecate these APIs in Chrome, and work toward removing them. Initial public proposalNone Search tagsMutationEvent <https://chromestatus.com/features#tags:MutationEvent>, DOMSubtreeModified <https://chromestatus.com/features#tags:DOMSubtreeModified>, DOMNodeInserted <https://chromestatus.com/features#tags:DOMNodeInserted>, DOMNodeRemoved <https://chromestatus.com/features#tags:DOMNodeRemoved>, DOMNodeRemovedFromDocument <https://chromestatus.com/features#tags:DOMNodeRemovedFromDocument>, DOMNodeInsertedIntoDocument <https://chromestatus.com/features#tags:DOMNodeInsertedIntoDocument>, DOMCharacterDataModified <https://chromestatus.com/features#tags:DOMCharacterDataModified> TAG reviewNone TAG review statusNot applicable Risks Interoperability and Compatibility There are technically 9 Mutation Events, but Chromium only implements 6 of them. Their use counters vary significantly: - DOMNodeInsertedIntoDocument: 0.006% - DOMNodeRemovedFromDocument: 0.012% - DOMCharacterDataModified: 0.016% - DOMNodeRemoved: 0.77% - DOMSubtreeModified: 0.81% - DOMNodeInserted: 1.58% The first three could likely be fairly easily removed after some time. The last three have quite significant usage, and more study and outreach will be required to bring this usage down below safe removal limits, which will take significant time. Tentatively, we're aiming for M126 as the last version of Chrome that supports the events above, ending July 30, 2024. *Gecko*: No signal ( https://github.com/whatwg/dom/issues/305#issuecomment-241686139) Old comments indicate support, but no official position yet. *WebKit*: No signal *Web developers*: No signals *Other signals*: WebView application risks Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications? None Debuggability Is this feature fully tested by web-platform-tests <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> ?No Flag name Requires code in //chrome?False Tracking bughttps://crbug.com/1446498 Estimated milestones Shipping on desktop 127 Shipping on Android 127 Shipping on WebView 127 Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5083947249172480 Links to previous Intent discussions This intent message was generated by Chrome Platform Status <https://chromestatus.com/>. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDgP1mWEoDABHmKfCXSSFO9ZyQDQ5p7h_TtN51ZnyvxSSg%40mail.gmail.com.
