animation-fill-mode

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.

CSS 属性 animation-fill-mode 设置 CSS 动画在执行之前和之后如何将样式应用于其目标。

尝试一下

animation-fill-mode: none; animation-delay: 1s; 
animation-fill-mode: forwards; animation-delay: 1s; 
animation-fill-mode: backwards; animation-delay: 1s; 
animation-fill-mode: both; animation-delay: 1s; 
<section class="flex-column" id="default-example"> <div>Animation <span id="playstatus"></span></div> <div id="example-element">Select a mode to start!</div> </section> 
#example-element { background-color: #1766aa; color: white; margin: auto; margin-left: 0; border: 5px solid #333; width: 150px; height: 150px; border-radius: 50%; display: flex; justify-content: center; align-items: center; flex-direction: column; } #playstatus { font-weight: bold; } .animating { animation: slide 1s ease-in 1; } @keyframes slide { from { background-color: orange; color: black; margin-left: 0; } to { background-color: orange; color: black; margin-left: 80%; } } 
"use strict"; window.addEventListener("load", () => { const el = document.getElementById("example-element"); const status = document.getElementById("playstatus"); function update() { status.textContent = "delaying"; el.className = ""; window.requestAnimationFrame(() => { window.requestAnimationFrame(() => { el.className = "animating"; }); }); } el.addEventListener("animationstart", () => { status.textContent = "playing"; }); el.addEventListener("animationend", () => { status.textContent = "finished"; }); const observer = new MutationObserver(() => { update(); }); observer.observe(el, { attributes: true, attributeFilter: ["style"], }); update(); });

使用简写属性 animation 一次性设置所有动画属性通常很方便。

语法

css
/* Single animation */ animation-fill-mode: none; animation-fill-mode: forwards; animation-fill-mode: backwards; animation-fill-mode: both; /* Multiple animations */ animation-fill-mode: none, backwards; animation-fill-mode: both, forwards, none;

值

none

当动画未执行时，动画将不会将任何样式应用于目标，而是已经赋予给该元素的 CSS 规则来显示该元素。这是默认值。

forwards

目标将保留由执行期间遇到的最后一个关键帧计算值。最后一个关键帧取决于animation-direction和animation-iteration-count的值：

animation-direction animation-iteration-count last keyframe encountered
normal even or odd 100% or to
reverse even or odd 0% or from
alternate even 0% or from
alternate odd 100% or to
alternate-reverse even 100% or to
alternate-reverse odd 0% or from
backwards

动画将在应用于目标时立即应用第一个关键帧中定义的值，并在animation-delay期间保留此值。第一个关键帧取决于animation-direction的值：

animation-direction first relevant keyframe
normal or alternate 0% or from
reverse or alternate-reverse 100% or to
both

动画将遵循forwards和backwards的规则，从而在两个方向上扩展动画属性。

备注： 当你在animation-*属性上指定多个以逗号分隔的值时，它们将根据值的数量以不同的方式分配给 animation-name 属性中指定的动画。有关更多信息，请参阅设置多个动画属性值。

正式语法

animation-fill-mode = 
 <single-animation-fill-mode># 

<single-animation-fill-mode> = 
 none |
 forwards |
 backwards |
 both

示例

你可以在以下示例中看到 animation-fill-mode 的效果。它演示了如何对于运行无限时间的动画，可以使其保持最终状态而不是恢复到原始状态（这是默认状态）。

HTML

html
<p>Move your mouse over the gray box!</p> <div class="demo"> <div class="growsandstays">This grows and stays big.</div> <div class="grows">This just grows.</div> </div>

CSS

css
.demo { border-top: 100px solid #ccc; height: 300px; } @keyframes grow { 0% { font-size: 0; } 100% { font-size: 40px; } } .demo:hover .grows { animation-name: grow; animation-duration: 3s; } .demo:hover .growsandstays { animation-name: grow; animation-duration: 3s; animation-fill-mode: forwards; }

更多示例请查看 CSS 动画 。

规范

Specification
CSS Animations Level 1
# animation-fill-mode
初始值none
适用元素all elements, ::before and ::after pseudo-elements
是否是继承属性否
计算值as specified
动画类型Not animatable

浏览器兼容性

参见