Close requests and close watchers #215
Description
WebKittens
@annevk and @othermaciej have both previously reviewed this
Title of the spec
Close signals and close watchers
URL to the spec
https://html.spec.whatwg.org/multipage/interaction.html#close-requests-and-close-watchers
URL to the spec's repository
https://github.com/WICG/close-watcher
Issue Tracker URL
No response
Explainer URL
No response
TAG Design Review URL
Mozilla standards-positions issue URL
mozilla/standards-positions#604
WebKit Bugzilla URL
No response
Radar URL
No response
Description
In addition to the WICG repository with the explainer, see the HTML Standard pull request: whatwg/html#9462
The main new API introduced here is the CloseWatcher API. But this spec also includes changes to unify dialog, popover, and fullscreen handling into a single "close watcher" concept, which is triggered by a platform-independent concept of "close request".
For macOS and keyboard-attached iOS devices, the close request would be the Esc key. For other iOS devices, there might not be a close request. This was previously discussed in WICG/close-watcher#11 ; see also https://github.com/WICG/close-watcher/blob/main/platform-implementation-notes.md . In such cases, it would still be ideal for the API to exist and be implemented, and just never triggered via user action, so that developers can write platform-agnostic code (e.g. centralizing their close logic into the close event handler of a CloseWatcher object).
Because of how close request gestures can serve multiple purposes, e.g. the Android back button/gesture being used to navigate session history, the specification has some anti-abuse measures to prevent the close signal gesture from being indefinitely captured by web developers using dialogs, popovers, or CloseWatchers. These measures might not be necessary in the macOS/iOS-with-keyboard ecosystem, where the Esc key is the only relevant gesture and it does not serve another purpose. But we think they're still reasonable, and should be implemented uniformly across platforms for interoperability. This was previously discussed from one angle in WICG/close-watcher#10.