使用 CSS transitions

这是一个实验中的功能
此功能某些浏览器尚在开发中，请参考浏览器兼容性表格以得到在不同浏览器中适合使用的前缀。由于该功能对应的标准文档可能被重新修订，所以在未来版本的浏览器中该功能的语法和行为可能随之改变。

CSS transitions 提供了一种在更改CSS属性时控制动画速度的方法。 其可以让属性变化成为一个持续一段时间的过程，而不是立即生效的。比如，将一个元素的颜色从白色改为黑色，通常这个改变是立即生效的，使用 CSS transitions 后该元素的颜色将逐渐从白色变为黑色，按照一定的曲线速率变化。这个过程可以自定义。

通常将两个状态之间的过渡称为隐式过渡（implicit transitions），因为开始与结束之间的状态由浏览器决定。

A CSS transition tells the browsder to draw the intermediate states between the initial and final states, showing the user a smooth transitions.

CSS transitions 可以决定哪些属性发生动画效果 (明确地列出这些属性)，何时开始 (设置 delay），持续多久 (设置 duration) 以及如何动画 (定义timing function，比如匀速地或先快后慢)。

Note: transition 可以不用厂商前缀，不过鉴于标准刚刚稳定，对于基于 Webkit的浏览器仍然需要厂商前缀。如果想兼容旧版本的浏览器那么也需要厂商前缀（例如Firefox 15 及之前版本, Opera 12 及之前版本)。详情见本页底部的兼容性表格。

哪些 CSS 属性可以动画?

网页制作者可以定义哪个属性以哪种方式动画，这样能制作出复杂的过渡。因为有些属性动画无意义，所以 可动画属性列表 是一个有限集合。

Note: 可动画的属性集将有变动，开发者应关注。

auto 值常常较复杂，规范指出不要在它上动画。一些用户代理，比如基于 Gecko 的，遵循这点；一些，比如基于 WebKit的，没有这么严格限制。在 auto 上动画结果可能不可预期，这取决于浏览器及其版本，应当避免使用。

同时应当留意这种情形，在插入元素（如 .appendChild()）或改变属性 display: none 后立即使用过渡, 元素将视为没有开始状态，始终处于结束状态。简单的解决办法，改变属性前用 window.setTimeout() 延迟几毫秒。

多个属性一起动画示例

HTML 内容

<body>
    <p>盒子的多个属性一起动画: width, height, background-color, transform. 将光标悬停在盒子上查看动画。</p>
    <div class="box"></div>
</body>

CSS 内容

.box {
    border-style: solid;
    border-width: 1px;
    display: block;
    width: 100px;
    height: 100px;
    background-color: #0000FF;
    -webkit-transition:width 2s, height 2s, 
        background-color 2s, -webkit-transform 2s;
    transition:width 2s, height 2s, background-color 2s, transform 2s;
}
.box:hover {
    background-color: #FFCCCC;
    width:200px;
    height:200px;
    -webkit-transform:rotate(180deg);
    transform:rotate(180deg);
}

定义过渡

CSS 过渡 由简写属性 transition 定义是最好的方式，可以避免属性值列表长度不一，节省调试时间。

也可以用下面子属性来控制过渡的各部分：

(注意下面示例中过渡无限循环是为了说明例子，过渡只是从开始到结束变化，如果需要循环，查看 animation 。)

transition-property
指定哪个或哪些 CSS 属性用于过渡。只有指定的属性才会在过渡中发生动画，其它属性仍如通常那样瞬间变化。
transition-duration
指定过渡的时长。或者为所有属性指定一个值，或者指定多个值，为每个属性指定不同的时长。

transition-duration: 0.5s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top transform -webkit-transform color;
    -webkit-transition-duration:0.5s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform -webkit-transform color;
    transition-duration:0.5s;
    transition-timing-function: ease-in-out;
}
.box1{
    transform: rotate(270deg);
    -webkit-transform: rotate(270deg);
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top transform -webkit-transform color;
    -webkit-transition-duration:0.5s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform -webkit-transformv color;
    transition-duration:0.5s;
    transition-timing-function: ease-in-out;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-duration: 1s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top -webkit-transform color;
    -webkit-transition-duration:1s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform color;
    transition-duration:1s;
    transition-timing-function: ease-in-out;
}
.box1{
    transform: rotate(270deg);
    -webkit-transform: rotate(270deg);
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top -webkit-transform transform color;
    -webkit-transition-duration:1s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform -webkit-transform color;
    transition-duration:1s;
    transition-timing-function: ease-in-out;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-duration: 2s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top transform -webkit-transform color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform -webkit-transform color;
    transition-duration:2s;
    transition-timing-function: ease-in-out;
}
.box1{
    transform: rotate(270deg);
    -webkit-transform: rotate(270deg);
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top transform -webkit-transform color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform -webkit-transform color;
    transition-duration:2s;
    transition-timing-function: ease-in-out;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-duration: 4s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top transform -webkit-transform color;
    -webkit-transition-duration:4s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform -webkit-transform color;
    transition-duration:4s;
    transition-timing-function: ease-in-out;
}
.box1{
    transform: rotate(270deg);
    -webkit-transform: rotate(270deg);
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top transform -webkit-transform color;
    -webkit-transition-duration:4s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top transform -webkit-transform color;
    transition-duration:4s;
    transition-timing-function: ease-in-out;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);
transition-timing-function
指定一个函数，定义属性值怎么变化。缓动函数 Timing functions 定义属性如何计算。多数 timing functions 由四点定义一个 bezier 曲线。也可以从 Easing Functions Cheat Sheet 选择缓动效果。

transition-timing-function: ease

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: ease;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: ease;
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: ease;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: ease;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-timing-function: linear

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: linear;
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: linear;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-timing-function: step-end

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: step-end;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: step-end;
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: step-end;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: step-end;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-timing-function: steps(4, end)

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: steps(4, end);
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: steps(4, end);
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-timing-function: steps(4, end);
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-timing-function: steps(4, end);
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);
transition-delay
指定延迟，即属性开始变化时与过渡开始发生时之间的时长。

transition-delay: 0.5s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:0.5s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:0.5s;
    transition-timing-function: linear;
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
     -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:0.5s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:0.5s;
    transition-timing-function: linear;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-delay: 1s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
     -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:1s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:1s;
    transition-timing-function: linear;
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:1s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:1s;
    transition-timing-function: linear;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-delay: 2s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:2s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:2s;
    transition-timing-function: linear;
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:2s;
    -webkit-transition-timing-function: linear;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:2s;
    transition-timing-function: linear;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

transition-delay: 4s

 <div class="parent">
  <div class="box">Lorem</div>
</div>
  
.parent { width: 250px; height:125px;}
.box {
    width: 100px;
    height: 100px;
    background-color: red;
    font-size: 20px;
    left: 0px;
    top: 0px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:4s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:4s;
    transition-timing-function: ease-in-out;
}
.box1{
    width: 50px;
    height: 50px;
    background-color: blue;
    color: yellow;
    font-size: 18px;
    left: 150px;
    top:25px;
    position:absolute;
    -webkit-transition-property: width height background-color font-size left top color;
    -webkit-transition-duration:2s;
    -webkit-transition-delay:4s;
    -webkit-transition-timing-function: ease-in-out;
    transition-property: width height background-color font-size left top color;
    transition-duration:2s;
    transition-delay:4s;
    transition-timing-function: ease-in-out;
}

function updateTransition() {
  var el = document.querySelector("div.box");
   
  if (el) {
    el.className = "box1";
  } else {
    el = document.querySelector("div.box1");
    el.className = "box";
  }
   
  return el;
}

var intervalID = window.setInterval(updateTransition, 7000);

简写语法：

div {
    transition: <property> <duration> <timing-function> <delay>;
}

检测过渡是否完成

当过渡完成时触发一个事件，在符合标准的浏览器下，这个事件是 transitionend, 在 WebKit 下是 webkitTransitionEnd. 详情查看页面底部的兼容性表格。 transitionend 事件提供两个属性:

propertyName
字符串，指示已完成过渡的属性。
elapsedTime
浮点数，指示当触发这个事件时过渡已运行的时间（秒）。这个值不受 transition-delay 影响。

照例可以用  element.addEventListener() 方法来监听这个事件：

el.addEventListener("transitionend", updateTransition, true);
Note: 如果取消了过渡则不会触发 transitionend 事件，因为在过渡完成前动画的属性值改变了。

当属性值列表长度不一致时

以 transition-property 的值列表长度为标准，如果某个属性值列表长度短于它的，则重复其值以长度一致， 例如:

div {
  transition-property: opacity, left, top, height;
  transition-duration: 3s, 5s;
}

将按下面这样处理:

div {
  transition-property: opacity, left, top, height;
  transition-duration: 3s, 5s, 3s, 5s;
}

类似地，如果某个属性的值列表长于 transition-property 的，将被截短。 例如:

div {
  transition-property: opacity, left;
  transition-duration: 3s, 5s, 2s, 1s;
}

将按下面这样处理:

div {
  transition-property: opacity, left;
  transition-duration: 3s, 5s;
}

简单例子

这个例子实现这样的效果：4s 过渡改变字体大小，2s 延迟——在元素上鼠标悬停时与开始动画效果之间：

#delay1 {
  position: relative;
  transition-property: font-size;
  transition-duration: 4s;
  transition-delay: 2s;
  font-size: 14px;
}

#delay1:hover {
  transition-property: font-size;
  transition-duration: 4s;
  transition-delay: 2s;
  font-size: 36px;
}

高亮菜单过渡效果

CSS 的一个常用地方是当鼠标悬停在菜单上时高亮此菜单，使用 transition 效果更佳。

HTML 内容

<div class="sidebar">
  <p><a class="menuButton" href="home">Home</a></p>
  <p><a class="menuButton" href="about">About</a></p>
  <p><a class="menuButton" href="contact">Contact Us</a></p>
  <p><a class="menuButton" href="links">Links</a></p>
</div>

CSS 内容

.menuButton {
  position: relative;
  transition-property: background-color, color;
  transition-duration: 1s;
  transition-timing-function: ease-out;
  text-align: left;
  background-color: grey;
  left: 5px;
  top: 5px;
  height: 26px;
  color: white;
  border-color: black;
  font-family: sans-serif;
  font-size: 20px;
  text-decoration: none;
  box-shadow: 2px 2px 1px black;
  padding: 2px 4px;
  border: solid 1px black;
}

.menuButton:hover {
  position: relative;
  transition-property: background-color, color;
  transition-duration: 1s;
  transition-timing-function: ease-out;
  background-color:white;
  color:black;
  box-shadow: 2px 2px 1px black;
}

这个 CSS 设置了菜单的外观，在:hover时，菜单里的元素的文字、颜色及背景色都发生了变化。

transition 让 JavaScript 效果更平滑

transition 是非常好的工具，可以让 JavaScript 效果平滑而不用修改 JavaScript。 看下面例子。

<p>随便点击某处来移动球</p>
<div id="foo"></div>

使用 JavaScript 将球移动到一个位置 ：

var f = document.getElementById('foo');
document.addEventListener('click', function(ev){
    f.style.left = (ev.clientX-25)+'px';
    f.style.top = (ev.clientY-25)+'px';
},false);

使用CSS 来平滑移动，只用简单地添加一个过渡 :

p {
  padding-left: 60px;
}

#foo {
  border-radius: 50px;
  width: 50px;
  height: 50px;
  background: #c00;
  position: absolute;
  top: 0;
  left: 0;
  transition:  all 1s;
}

演示： http://jsfiddle.net/RwtHn/5/

规范

Specification Status Comment
CSS Transitions Working Draft Initial specification.

浏览器兼容性

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 1.0 -webkit
26.0		 4.0 (2.0) -moz
16.0 (16.0)		 10 10.5 -o
12.10		 3.2 -webkit
transitionend event 1.0[1]
26.0		 4.0 (2.0) 10 10.5[2]
12
12.10		 3.2[1]
6.0
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 2.1 4.0 (2.0) -moz
16.0 (16.0)		 10 10 -o
12.10		 3.2
transitionend event 2.1[1] 4.0 (2.0) 10 10[2]
12
12.10		 3.2[1]

另见