Vue 进入/离开动画效果

<template>  <div>    <button v-on:click="show = !show">      Toggle    </button>    <transition name="fade">      <p v-if="show">hello</p>    </transition>  </div></template><script>  export default {    data: function() {      return {        show: true      }    }  }</script><style>  .fade-enter-active,  .fade-leave-active {    transition: opacity .5s  }    .fade-enter,  .fade-leave-to {    opacity: 0  }</style>