On Thu, 9 Apr 2026 at 03:44, Mukundan Kumar <[email protected]> wrote:
> Hi, > > Is this event deprecated for all websites or only top 50 websites. Is > there any detailed roll out plan for this? > The plan is here <https://developer.chrome.com/docs/web-platform/deprecating-unload>. M146 will be the first version where this goes beyond top-50, F > > On Sunday, May 7, 2023 at 10:43:07 PM UTC-7 Fergal Daly wrote: > >> Contact emails >> >> [email protected], [email protected] >> >> Explainer >> >> >> https://github.com/fergald/docs/blob/master/explainers/permissions-policy-deprecate-unload.md >> >> Specification >> >> https://github.com/whatwg/html/pull/7915 >> >> Summary >> >> A Permission-Policy for creating unload event listeners will be added. >> >> Initially, the default policy will be set to allow. From there, Chrome >> will gradually migrate the default policy to deny (i.e. increasingly >> disallow the creation of unload event listeners, eventually reaching a >> state where deny fully becomes the default policy). The ultimate goal is >> to remove support for unload event. >> >> Blink component >> >> Blink>PermissionsAPI >> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EPermissionsAPI> >> >> Motivation >> >> The unload event is extremely unreliable. It is ignored in most cases by >> all mobile browsers except Firefox on Android. Furthermore, in Safari, the >> unload event is ignored on both desktop & mobile platforms. >> >> In the current state, unload is a major BFCache blocker (~18 percentage >> points reduction of hit rate for Chrome). >> >> The change will unlock a large fraction of that hit-rate while providing >> an opt-out for those who need more time to migrate. It also sends a clear >> signal that unload should not be used in new development. >> >> Sidenote: the spec was changed to say that unload should only run if the >> page cannot enter BFCache, which reflects Safari’s behavior, However >> neither Chrome nor Mozilla have implemented this behavior. In Chrome's >> case, we believe that this would suddenly break various sites and would >> make it hard for developers to know if/when unload may run. >> >> >> Initial public proposal >> >> None >> >> TAG review >> >> https://github.com/w3ctag/design-reviews/issues/738 >> >> TAG review status >> >> Pending >> >> Risks >> >> Interoperability and Compatibility >> >> If no other browsers implement this, there is a risk that devs continue >> to use unload widely and pages malfunction on chrome. However given that >> alternatives to unload exist it seems entirely possible for sites that are >> actively maintained to move off unload. >> >> Gecko: ( >> https://github.com/mozilla/standards-positions/issues/691#issuecomment-1484997320) >> It's possible that pages are depending on `unload` handlers in subframes >> for functionality even without any main frame navigation. We should try to >> understand how common this is before breaking it. It should be possible to >> measure how often subframe unloads fire when the mainframe is not >> navigating. This will give us an upper bound on the size of the problem, - >> Chrome: we have landed code to measure the occurrence of unload in >> different scenarios. We will report back the findings. >> >> WebKit: https://github.com/WebKit/standards-positions/issues/127 >> >> Web developers: Positive ( >> https://groups.google.com/a/chromium.org/g/bfcache-dev/c/zTIMx7u4uxo/m/-M4IS6LDBgAJ) >> The web communities we reached out had positive reactions to our proposal >> and we have not heard about any concrete blockers. >> >> 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? >> >> On WebView, we will introduce the Permissions-Policy but not move the >> default to "deny". BFCache does not work on WebView, so the benefit is >> lower. Meanwhile the risk seems higher as we have far less visibility into >> the HTML being run in WebViews. A roll-out to WebView should be done >> independently and in consultation with the WebView team. >> >> >> Debuggability >> >> None >> >> Is this feature fully tested by web-platform-tests >> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> >> ? >> >> Yes >> >> Flag name >> >> None >> >> Requires code in //chrome? >> >> False >> >> Estimated milestones >> >> M115 for availability of Permissions-Policy >> >> M115 is the earliest we would start to disable unload, however >> >> Link to entry on the Chrome Platform Status >> >> https://chromestatus.com/feature/5579556305502208 >> >> -- 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 [email protected]. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAAozHLnwAsCPBHu9c1%3DUwiK%2Bq4Cg%2Bp7EuLwK4to6RruRU%2BZz3Q%40mail.gmail.com.
