原理：CSS3中的transition属性
<!DOCTYPE html>
<html lang="en" dir="ltr">
<head>
<meta charset="utf-8">
<title>Vue中CSS动画原理</title>
<script src="./vue.js"></script>
<style media="screen">
.fade-enter,
.fade-leave-to{
opacity:0;
}
.fade-enter-active,
.fade-leave-active{
transition:opacity 3s;
}
</style>
</head>
<body>
<div id="root">
<transition name="fade">
<div v-if="show">
hello world
</div>
</transition>
<button @click="handleClick">change</button>
</div>
<script type="text/javascript">
var vm = new Vue({
el: '#root',
data: {
show: true
},
methods: {
handleClick: function() {
this.show = !this.show
}
}
})
</script>
</body>
</html>