Intent to Ship: Wheel event momentum

[Chromestatus]

Contact emails

mus...@chromium.org

Specification

https://w3c.github.io/pointerevents/#dom-wheelevent-momentum

Summary

The wheel events on many native platforms simulate scrolling inertia: the events continue to fire for a while after the user has lifted the finger from the trackpad after a fling interaction. This feature exposes a momentum attribute in wheel events which is true only for those simulated events, differentiating them from the events fired during the physical scroll interaction. This lets web developers ignore fling events or customize rich fling effects.

Blink component

Blink>Input

Web Feature ID

Missing feature

Motivation

No information provided

Initial public proposal

No information provided

TAG review

This feature is too small and non-controversial to justify a TAG review.

TAG review status

Not applicable

Goals for experimentation

None

Risks

Interoperability and Compatibility

No information provided

Gecko: Positive (https://lists.w3.org/Archives/Public/public-pointer-events/2026JanMar/0148.html#:~:text=smaug%3A%20just%20having%20a%20flag%20should%20be%20easy.%20we%27ll%20just%20have%20to%20do%20%0Asomething%20on%20linux) Supported the feature during PEWG meeting on 2026-03-11.

WebKit: No signal

Web developers: Positive (https://github.com/w3c/pointerevents/issues/587) See the dev discussion and also many thumbs-up emojis.

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?

No information provided

Debuggability

No information provided

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

No

Is this feature fully tested by web-platform-tests?

No

Flag name on about://flags

No information provided

Finch feature name

WheelEventMomentum

Rollout plan

Will ship enabled for all users

Requires code in //chrome?

False

Tracking bug

https://crbug.com/40704952

Estimated milestones

Shipping on desktop	151
Shipping on Android	151
Shipping on WebView	151

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).

No information provided

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/6631012282007552?gate=5864164607262720

This intent message was generated by Chrome Platform Status.

[Mike Taylor]

Can we file real vendor position issues for Gecko and WebKit (but, nice to see the comments from Olli)?

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[Mustaq Ahmed]

Filed standard position requests: https://github.com/mozilla/standards-positions/issues/1425 and https://github.com/WebKit/standards-positions/issues/688

[Yoav Weiss (@Shopify)]

Is it possible to share an explainer (even an inline one) RE the use cases for this and how we expect developers to use this?

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[Rick Byers]

Happy to see this ship (after apparently dropping the ball on it myself over a decade ago)!

Shouldn't there at least be a WPT for the existence of the `momentum` (i.e. in the IDL tests for WheelEvent)?

 
Ideally there'd also be a test that verifies the bool gets plumbed through, i,.e. by extending webdriver wheel actions. Might web developers need that for proper automated testing of these advanced scrolling UX? Can you at least file a bug to track the missing automation here? I'm OK not blocking shipping on that if you prefer.

Rick

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