1. 页面加载时就有动画效果，transition appear appear-active-class
注意：引入第三方库animate.css库
<body>
<div id="demo">
<button @click="show = !show">click me</button>
<transition name="fade"
enter-active-class="animated swing"
leave-active-class="animated shake"
appear
appear-active-class="animated swing">
<div v-if="show" class="de">sfsf</div>
</transition>
</div>
<script>
new Vue({
el: '#demo',
data: {
show: true
}
})
</script>
</body>