Hi, Is this event deprecated for all websites or only top 50 websites. Is there any detailed roll out plan for this?
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/7f1fe93f-4dab-4480-bc54-adef1ee86a24n%40chromium.org.
