Web-Facing Change PSA: Continue running transitions when switching to initial transition value.
Chromestatus
Contact emails
fla...@chromium.orgSpecification
https://www.w3.org/TR/css-transitions-1/#startingSummary
When the transition related properties change, they are only supposed to affect newly started transitions. This means that if you change the transition properties, unless you also change the properties which have active transition animations, those transition animations will continue with the previously specified duration, easing, etc. Blink incorrectly canceled transitions when the transition property was set to "none", even though it doesn't cancel them if you only change the transition-duration. With this feature, blink will be consistent with webkit and gecko, allowing active transitions to continue running, unless/until their property value changes triggering a new transition update.
Blink component
Blink>AnimationTAG review
NoneTAG review status
Not applicableRisks
Interoperability and Compatibility
This change brings chromium / blink into alignment with the other two major browser engines. If developers were only testing on chromium, they may have transitions run which did not used to on chromium. However, given this is what is happening on other browsers it will help ensure they can build a consistent experience. According to our use counter, this may affect up to 4.5% of page loads: https://chromestatus.com/metrics/feature/timeline/popularity/2914
Gecko: Shipped/Shipping
WebKit: Shipped/Shipping
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?
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?
NoFlag name on about://flags
Experimental Web Platform featuresFinch feature name
CSSTransitionNoneRunningTransitionsFixRollout plan
Will ship enabled for all usersRequires code in //chrome?
FalseMeasurement
The CSSTransitionCancelledByRemovingStyle counter measures how often this change will result in a transition that is no longer canceled: https://chromestatus.com/metrics/feature/timeline/popularity/2914Sample links
https://jsbin.com/tesuliz/edit?html,css,js,output
Estimated milestones
| Shipping on desktop | 139 |
| Shipping on Android | 139 |
| Shipping on WebView | 139 |
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