Contact emailsmas...@chromium.org ExplainerNone
Specificationhttps://w3c.github.io/uievents/#legacy-event-types Summary 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 now be migrated to Mutation Observer. Mutation event support will be disabled by default starting in Chrome 127, around July 30, 2024. Code should be migrated before that date to avoid site breakage. If more time is needed, there are a few options: - The Mutation Events Deprecation Trial ( https://developer.chrome.com/origintrials/#/view_trial/919297273937002497) can be used to re-enable the feature for a limited time on a given site. This can be used through Chrome 134, ending March 25, 2025. - A MutationEventsEnabled enterprise policy ( https://chromeenterprise.google/policies/#MutationEventsEnabled) can also be used for the same purpose, also through Chrome 134. Please see this blog post for more detail: https://developer.chrome.com/blog/mutation-events-deprecation Report bugs here: https://issues.chromium.org/new?component=1456718&template=1948649 Blink componentBlink>DOM <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EDOM> 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 Chromium Trial NameMutationEvents Origin Trial documentation link https://developer.chrome.com/blog/mutation-events-deprecation WebFeature UseCounter namekDOMNodeRemovedEvent Risks Interoperability and Compatibility There are technically 9 Mutation Events, but Chromium only implements 6 of them. Their use counters vary significantly: - DOMNodeInsertedIntoDocument: 0.008% - DOMNodeRemovedFromDocument: 0.009% - DOMCharacterDataModified: 0.011% - DOMNodeRemoved: 0.73% - DOMSubtreeModified: 0.68% - DOMNodeInserted: 1.086% Chrome has shipped an experiment since M124 that disables all Mutation Events for 99% of users of Canary, Dev, and Beta versions of Chrome. Very few bugs have been filed in the intervening months, and all that were filed have been resolved quickly via the site owner making changes to not rely on the deprecated events. This gives me significant confidence that removing the events will not be as big of a deal as the use counters would suggest. Still, due to the still-high numbers, extreme care will be taken in the removal process. I plan to disable the events via Finch only, so that if issues are encountered, Finch will be a safe way to re-enable the events. Additionally, there are the deprecation trial and enterprise policies to offer an easy relief valve for affected sites. *Gecko*: Positive (https://github.com/mozilla/standards-positions/issues/807) "very strong positive position" *WebKit*: No signal ( https://github.com/WebKit/standards-positions/issues/192) *Web developers*: No signals *Other signals*: Activation This npm package attempts to polyfill Mutation Events using Mutation Observer: https://www.npmjs.com/package/mutation-events. 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 Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?Yes 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 on chrome://flagsmutation-events Finch feature nameMutationEvents Requires code in //chrome?False Tracking bughttps://crbug.com/1446498 Estimated milestones Shipping on desktop 127 Origin trial desktop first 124 Origin trial desktop last 134 Shipping on Android 127 OriginTrial Android last 134 OriginTrial Android first 124 Shipping on WebView 127 OriginTrial webView last 134 OriginTrial webView first 124 Anticipated spec changes Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way). None Link to entry on the Chrome Platform Status https://chromestatus.com/feature/5083947249172480?gate=5111010140094464 Links to previous Intent discussionsIntent to Deprecate: https://groups.google.com/a/chromium.org/g/blink-dev/c/qDsKRU-cQ_4/m/isA1mZ_aAAAJ Intent to Experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/z-VIfSOco4k/m/KDz9c_goAAAJ 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%3DNeDjonGju3YX1WkXtEJrMGLo4bH9AqtwV0QoqvopdGNioAg%40mail.gmail.com.
