@keyframes

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句法
描述
形式句法
范例
规范
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@keyframes CSS at-rule controls the intermediate steps in a CSS animation sequence by defining styles for keyframes (or waypoints) along the animation sequence. This gives more control over the intermediate steps of the animation sequence than transitions .

句法

@keyframes slidein {
  from {
    transform: translateX(0%);
  }
  to {
    transform: translateX(100%);
  }
}

值

<custom-ident>
from: A starting offset of 0% .
to: An ending offset of 100% .
<percentage>

描述

JavaScript can access the @keyframes at-rule with the CSS object model interface CSSKeyframesRule .

To use keyframes, create a @keyframes rule with a name that is then used by the animation-name property to match an animation to its keyframe declaration. Each @keyframes rule contains a style list of keyframe selectors, which specify percentages along the animation when the keyframe occurs, and a block containing the styles for that keyframe.

You can list the keyframe percentages in any order; they will be handled in the order they should occur.

Valid keyframe lists

If a keyframe rule doesn't specify the start or end states of the animation (that is, 0% / from and 100% / to ), browsers will use the element's existing styles for the start/end states. This can be used to animate an element from its initial state and back.

Properties that can't be animated in keyframe rules are ignored, but supported properties will still be animated.

Resolving duplicates

If multiple keyframe sets exist for a given name, the last one encountered by the parser is used. @keyframes rules don't cascade, so animations never derive keyframes from more than one rule set.

If a given animation time offset is duplicated, all keyframes in the @keyframes rule for that percentage are used for that frame. There is cascading within a @keyframes rule if multiple keyframes specify the same percentage values.

When properties are left out of some keyframes

Properties that aren't specified in every keyframe are interpolated if possible — properties that can't be interpolated are dropped from the animation. For example:

@keyframes identifier {
  0% { top: 0; left: 0; }
  30% { top: 50px; }
  68%, 72% { left: 50px; }
  100% { top: 100px; left: 100%; }
}

在这里， top property animates using the 0% , 30% ，和 100% keyframes, and left animates using the 0% , 68% , 72% and 100% keyframes.

When a keyframe is defined multiple times

If a keyframe is defined multiple times but not all affected properties are in each keyframe, all values specified in these keyframes are considered. For example:

@keyframes identifier {
  0% { top: 0; }
  50% { top: 30px; left: 20px; }
  50% { top: 10px; }
  100% { top: 0; }
}

In this example, at the 50% keyframe, the values used are top: 10px and left: 20px .

Cascading keyframes are supported starting in Firefox 14.

`!important` in a keyframe

Declarations in a keyframe qualified with !important 被忽略。

@keyframes important1 {
  from { margin-top: 50px; }
  50%  { margin-top: 150px !important; } /* ignored */
  to   { margin-top: 100px; }
}
@keyframes important2 {
  from { margin-top: 50px;
         margin-bottom: 100px; }
  to   { margin-top: 150px !important; /* ignored */
         margin-bottom: 50px; }
}

形式句法

@keyframes <keyframes-name> {
  <keyframe-block-list>
}where 
<keyframes-name> = <custom-ident> | <string>
<keyframe-block-list> = <keyframe-block>+
where 
<keyframe-block> = <keyframe-selector># {
  <declaration-list>
}
where 
<keyframe-selector> = from | to | <percentage>

范例

CSS animation examples

见使用 CSS 动画范例。

规范

规范	状态	注释
CSS 动画 The definition of '@keyframes' in that specification.	工作草案

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`@keyframes`	Chrome 完整支持 43	Edge 完整支持 12	Firefox 完整支持 16 注意事项完整支持 16 注意事项注意事项 `@keyframes` is unsupported in scoped stylesheets in Firefox ( bug 830056 ). 完整支持 Prefixed Prefixed Implemented with the vendor prefix: -webkit- 完整支持 Prefixed Implemented with the vendor prefix: -webkit- Disabled `layout.css.prefixes.webkit` preference (needs to be set to `true` ). To change preferences in Firefox, visit about:config. 完整支持 5 Prefixed Prefixed Implemented with the vendor prefix: -moz-	IE 完整支持 10	Opera 完整支持 30 完整支持 30 Prefixed Implemented with the vendor prefix: -webkit- 不支持 12.1 — 15 不支持 12 — 15 Prefixed Prefixed Implemented with the vendor prefix: -o-	Safari 完整支持 9	WebView Android 完整支持 43	Chrome Android 完整支持 43	Firefox Android 完整支持 16 完整支持 16 Prefixed Implemented with the vendor prefix: -webkit- 完整支持 Prefixed Implemented with the vendor prefix: -webkit- Disabled `layout.css.prefixes.webkit` preference (needs to be set to `true` ). To change preferences in Firefox, visit about:config. 完整支持 5 Prefixed Prefixed Implemented with the vendor prefix: -moz-	Opera Android 完整支持 30 完整支持 30 Prefixed Implemented with the vendor prefix: -webkit- 不支持 12.1 — 14 不支持 12 — 14 Prefixed Prefixed Implemented with the vendor prefix: -o-	Safari iOS 完整支持 9	Samsung Internet Android 完整支持 4.0
Ignore `!important` declarations	Chrome 完整支持 45	Edge 完整支持 79	Firefox 完整支持 19	IE 不支持 No	Opera 完整支持 32	Safari 完整支持 10.1	WebView Android 完整支持 45	Chrome Android 完整支持 45	Firefox Android 完整支持 19	Opera Android 完整支持 32	Safari iOS 完整支持 10.3	Samsung Internet Android 完整支持 5.0

图例

完整支持
不支持
见实现注意事项。
用户必须明确启用此特征。
要求使用供应商前缀或不同名称。

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元数据

最后修改： Jul 22, 2020

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