Animation - Web APIs 编辑

The Animation interface of the Web Animations API represents a single animation player and provides playback controls and a timeline for an animation node or source.

Constructor

Animation()

Creates a new Animation object instance.

Properties

Animation.currentTime

The current time value of the animation in milliseconds, whether running or paused. If the animation lacks a timeline, is inactive or hasn't been played yet, its value is null.

Animation.effect

Gets and sets the AnimationEffectReadOnly associated with this animation. This will usually be a KeyframeEffect object.

Animation.finished Read only

Returns the current finished Promise for this animation.

Animation.id

Gets and sets the String used to identify the animation.

Animation.pending Read only

Indicates whether the animation is currently waiting for an asynchronous operation such as initiating playback or pausing a running animation.

Animation.playState Read only

Returns an enumerated value describing the playback state of an animation.

Animation.playbackRate

Gets or sets the playback rate of the animation.

Animation.ready Read only

Returns the current ready Promise for this animation.

animation.replaceState

Returns the replace state of the animation. This will be active if the animation has been replaced, or persisted if Animation.persist() has been invoked on it.

Animation.startTime

Gets or sets the scheduled time when an animation's playback should begin.

Animation.timeline

Gets or sets the timeline associated with this animation.

Event handlers

Animation.oncancel

Gets and sets the event handler for the cancel event.

Animation.onfinish

Gets and sets the event handler for the finish event.

animation.onremove

Allows you to set and run an event handler that fires when the animation is removed (i.e., put into an active replace state).

Methods

Animation.cancel()

Clears all keyframeEffects caused by this animation and aborts its playback.

animation.commitStyles()

Commits the end styling state of an animation to the element being animated, even after that animation has been removed. It will cause the end styling state to be written to the element being animated, in the form of properties inside a style attribute.

Animation.finish()

Seeks either end of an animation, depending on whether the animation is playing or reversing.

Animation.pause()

Suspends playing of an animation.

animation.persist()

Explicitly persists an animation, when it would otherwise be removed due to the browser's Automatically removing filling animations behavior.

Animation.play()

Starts or resumes playing of an animation, or begins the animation again if it previously finished.

Animation.reverse()

Reverses playback direction, stopping at the start of the animation. If the animation is finished or unplayed, it will play from end to beginning.

Animation.updatePlaybackRate()

Sets the speed of an animation after first synchronizing its playback position.

Automatically removing filling animations

It is possible to trigger a large number of animations on the same element. If they are indefinite (i.e., forwards-filling), this can result in a huge animations list, which could create a memory leak. For this reason, modern browsers have implemented the part of the Web Animations spec that automatically removes overriding forward filling animations, unless the developer explicitly specifies to keep them.

You can see this in action in our simple replace indefinite animations demo. The related JavaScript features are:

• animation.commitStyles() for commiting the end styling state of an animation to the element being animated, even after that animation has been removed.
• animation.onremove for setting and running an event handler that fires when the animation is removed (i.e., put into an active replace state).
• animation.persist() for when you explicitly want an animations to be retained.
• animation.replaceState to return the replace state of the animation. This will be active if the animation has been removed, or persisted if persist() has been invoked.

Accessibility concerns

Blinking and flashing animation can be problematic for people with cognitive concerns such as Attention Deficit Hyperactivity Disorder (ADHD). Additionally, certain kinds of motion can be a trigger for Vestibular disorders, epilepsy, and migraine, and Scotopic sensitivity.

Consider providing a mechanism for pausing or disabling animation, as well as using the Reduced Motion Media Query to create a complimentary experience for users who have expressed a preference for no animated experiences.

• Designing Safer Web Animation For Motion Sensitivity · An A List Apart Article 
• An Introduction to the Reduced Motion Media Query | CSS-Tricks
• Responsive Design for Motion | WebKit
• MDN Understanding WCAG, Guideline 2.2 explanations
• Understanding Success Criterion 2.2.2  | W3C Understanding WCAG 2.0

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Web Animations API