Web-Facing Change PSA: Respect overscroll-behavior on non-scrollable scroll containers
Chromestatus
Contact emails
fla...@chromium.org , perry...@gmail.comSpecification
https://www.w3.org/TR/css-overscroll-1/#propdef-overscroll-behaviorSummary
The overscroll-behavior applies to all scroll container elements, regardless of whether those elements currently have overflowing content or are user scrollable. Developers can use overscroll-behavior to prevent scroll propagation on an `overflow: hidden` backdrop or an `overflow: auto` element without needing to consider whether it will currently be overflowing.
Blink component
Blink>ScrollWeb Feature ID
overscroll-behaviorTAG review
NoneTAG review status
Not applicableRisks
Interoperability and Compatibility
This should be implemented on other browsers as well, as it matches the specification. However, until this happens there are compatibility risks that some sites may over accidentally set overscroll-behavior on elements which don't currently apply today (either overflow: auto or not having overflow) and will start applying, or that developers will rely on this behavior and have accidental scroll chaining in other browsers until they implement it as well. This change will affect a large number of sites per https://chromestatus.com/metrics/feature/timeline/popularity/5596 . I have done compat analysis of many of the top sites affected by this in https://issues.chromium.org/issues/41371072#comment45 and found it to either not have a meaningful impact or to better honor the developer specified intent.
Gecko : No signal
WebKit : No signal
Web developers : No signals
Other signals :
Ergonomics
This improves the ergonomics of overscroll-behavior, fixing the current unpredictable layout dependent behavior we have today.
Activation
It may be difficult for developers to take advantage of this fix before it is adopted in other browsers as it is likely not possible to feature detect. They could remove pre-existing hacks to get this functionality (i.e. ensuring 1px overflow) on supporting chromium browsers.
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
None
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
YesIs this feature fully tested by web-platform-tests ?
YesFlag name on about://flags
NoneFinch feature name
OverscrollBehaviorRespectedOnAllScrollContainersRollout plan
Will ship enabled for all usersRequires code in //chrome?
FalseMeasurement
The OverscrollBehaviorOnNonScrollableScrollContainer feature counter measures how often this new behavior is or would be triggered. https://chromestatus.com/metrics/feature/timeline/popularity/5596Sample links
https://ebidel.github.io/demos/chatbox.html
https://codepen.io/rctneil/pen/rJYONj
Estimated milestones
No milestones specified
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