Element.animate() - Web APIs 编辑

The Element interface's animate() method is a shortcut method which creates a new Animation, applies it to the element, then plays the animation. It returns the created Animation object instance.

Elements can have multiple animations applied to them. You can get a list of the animations that affect an element by calling Element.getAnimations().

Syntax

var animation = element.animate(keyframes, options); 

Parameters

keyframes

Either an array of keyframe objects, or a keyframe object whose property are arrays of values to iterate over. See Keyframe Formats for more details.

options

Either an integer representing the animation's duration (in milliseconds), or an Object containing one or more timing properties: 

id Optional

A property unique to animate(): a DOMString with which to reference the animation.

delay Optional

The number of milliseconds to delay the start of the animation. Defaults to 0.

direction Optional

Whether the animation runs forwards (normal), backwards (reverse), switches direction after each iteration (alternate), or runs backwards and switches direction after each iteration (alternate-reverse). Defaults to "normal".

duration Optional

The number of milliseconds each iteration of the animation takes to complete. Defaults to 0. Although this is technically optional, keep in mind that your animation will not run if this value is 0.

easing Optional

The rate of the animation's change over time. Accepts the pre-defined values "linear", "ease", "ease-in", "ease-out", and "ease-in-out", or a custom "cubic-bezier" value like "cubic-bezier(0.42, 0, 0.58, 1)". Defaults to "linear".

endDelay Optional

The number of milliseconds to delay after the end of an animation. This is primarily of use when sequencing animations based on the end time of another animation. Defaults to 0. 

fill Optional

Dictates whether the animation's effects should be reflected by the element(s) prior to playing ("backwards"), retained after the animation has completed playing ("forwards"), or both. Defaults to "none".

iterationStart Optional

Describes at what point in the iteration the animation should start. 0.5 would indicate starting halfway through the first iteration for example, and with this value set, an animation with 2 iterations would end halfway through a third iteration. Defaults to 0.0.

iterations Optional

The number of times the animation should repeat. Defaults to 1, and can also take a value of Infinity to make it repeat for as long as the element exists.

You can also include a composite operation or iteration composite operation in your options list:

composite Optional

Determines how values are combined between this animation and other, separate animations that do not specify their own specific composite operation. Defaults to replace.

• add dictates an additive effect, where each successive iteration builds on the last. For instance with transform, a translateX(-200px) would not override an earlier rotate(20deg) value but result in translateX(-200px) rotate(20deg).
• accumulate is similar but a little smarter: blur(2) and blur(5) become blur(7), not blur(2) blur(5).
• replace overwrites the previous value with the new one. 

iterationComposite Optional

Determines how values build from iteration to iteration in this animation. Can be set to accumulate or replace (see above). Defaults to replace.

Return value

Returns an Animation.

Examples

In the demo Down the Rabbit Hole (with the Web Animation API), we use the convenient animate() method to immediately create and play an animation on the #tunnel element to make it flow upwards, infinitely. Notice the array of objects passed as keyframes and also the timing options block.

document.getElementById("tunnel").animate([
  // keyframes
  { transform: 'translateY(0px)' },
  { transform: 'translateY(-300px)' }
], {
  // timing options
  duration: 1000,
  iterations: Infinity
});

Implicit to/from keyframes

In newer browser versions, you are able to set a beginning or end state for an animation only (i.e. a single keyframe), and the browser will infer the other end of the animation if it is able to. For example, consider this simple animation — the Keyframe object looks like so:

let rotate360 = [
  { transform: 'rotate(360deg)' }
];

We have only specified the end state of the animation, and the beginning state is implied.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Web Animations API
• Element.getAnimations()
• Animation