I recall that some of this usage was feature detected: if mutation events are supported, use them; otherwise, use something else. Unfortunately, that makes it difficult to estimate the expected number of breakages. I agree though that it would be nice to understand the type of usage that still exists and the likelihood of real breakage
On Wed, May 15, 2024 at 9:27 PM Yoav Weiss (@Shopify) < yoavwe...@chromium.org> wrote: > > > On Wed, May 15, 2024 at 9:03 PM Mason Freed <mas...@chromium.org> wrote: > >> 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% >> > > 1% is a *lot*. Did UKM reveal anything interesting about this usage? Do we > know if all of it is driven by site content, vs e.g. extensions? > > >> 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 >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM%3DNeDjonGju3YX1WkXtEJrMGLo4bH9AqtwV0QoqvopdGNioAg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > 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/CAOmohSJzmUKZo5K0TwixDRx0J5JfcNzugO3C%2BPVac-sB-3M-0g%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohSJzmUKZo5K0TwixDRx0J5JfcNzugO3C%2BPVac-sB-3M-0g%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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