Contact emails
[email protected]

Explainer
https://github.com/explainers-by-googlers/scroll-triggered-animations


Specification
https://drafts.csswg.org/css-animations-2/#timeline-triggers


Design docs

https://github.com/explainers-by-googlers/scroll-triggered-animations/blob/main/README.md


Summary
This feature adds scroll-position-based control of animations, eg playing, 
pausing, and resetting an animation. A common pattern on pages across the web 
is to kick off an animation when a scroll position is reached. Developers often 
do this by using JavaScript to manually detect that an element is within its 
scroll container's viewport and to kick off a corresponding animation (eg 
perhaps sliding that element into view). Many of such use cases are based on 
information that can be provided declaratively. This feature gives authors the 
ability to create such interactions declaratively via CSS, allowing the user 
agent to offload the handling of this interaction to a worker thread. The API 
also includes JavaScript interfaces that allow the feature to be extended to 
web animations in addition to CSS animations.


Blink component
Blink>CSS


Web Feature ID
Missing feature


Motivation
Kicking off animations after having reached a desired scroll position is a 
common pattern on the web. Achieving this requires JavaScript to know when to 
trigger an animation. However, in many cases, all the information needed for 
many use cases can be declaratively specified. This feature provides authors a 
robust, reliable, performant and convenient way to set up such animations in 
response to scrolling.


Initial public proposal
https://github.com/w3c/csswg-drafts/issues/8942


TAG review
https://github.com/w3ctag/design-reviews/issues/1167


TAG review status
Pending


Risks




Interoperability and Compatibility
No information provided

Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1315)

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/576)

Web developers: No signals

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)?
Yes


Is this feature fully tested by web-platform-tests?
Yes
https://wpt.fyi/results/?label=master&label=experimental&aligned&q=scroll-animations%2Fanimation-trigger


DevTrial instructions
https://github.com/explainers-by-googlers/scroll-triggered-animations/blob/main/DEV_TRIALS.md


Flag name on about://flags
No information provided


Finch feature name
No information provided


Non-finch justification
No information provided


Rollout plan
Will ship enabled for all users


Requires code in //chrome?
False


Tracking bug
https://crbug.com/390314945


Availability expectation
Feature is expected to become available on WebPlatform Baseline.


Adoption expectation
We expect the feature to meet the needs of many scroll related animation use 
cases on the web.


Adoption plan
We plan to work with interested developers (of which we have at least 2 at the 
moment). We also plan to have a blog post.


Estimated milestones


Shipping on desktop 144

DevTrial on desktop 144

Shipping on Android 144

DevTrial on Android 144

Shipping on WebView 144




Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop 
issues. Please list open issues (eg links to known github issues in the project 
for the feature specification) whose resolution may introduce web 
compat/interop risk (eg, changing to naming or structure of the API in a 
non-backward-compatible way).
This feature is also intended to be supported via the web animations API but 
only the CSS animations spec is up to date. We expect the Web Animations spec 
to be closely related to the CSS spec/syntax and plan to update the Web 
Animations spec after addressing any feedback that arises from the CSS spec. We 
filed CSS working group issue https://github.com/w3c/csswg-drafts/issues/13010 
for feedback on the CSS spec.


Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5181996801982464?gate=5104214340272128


Links to previous Intent discussions
Intent to Prototype: 
https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAA6pwF6yEmATfHMv4RCp%2B6F_ufem%2Bt3%3D4maF15ySCKGXfCxb3w%40mail.gmail.com
Ready for Trial: 
https://groups.google.com/a/chromium.org/g/blink-dev/c/Gw42-BxHqcs/m/baT_KRxkAgAJ



This intent message was generated by Chrome Platform Status.

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