<div>
 <button @click="show = !show">show toggle</button>
 <transition name="fade"> //fade 自定义名称
  <p v-if="show">hello</p>
 </transition>
</div>

<style>
.fade-enter-active{   
 transition: opacity .5s;   //类名：隐藏到显示过程所需要的时间
}
.fade-enter {      // 类名:初始化状态
 opacity: 0;
}
</style>

<div>
 <button @click="show = !show">show toggle</button>
 <transition name="fade"> //fade 自定义名称
  <p v-if="show">hello</p>
 </transition>
</div>

<style>
.fade-enter-active {    //类名：隐藏到显示过程所需要的时间
 animation: bounce-in .5s;
}
.fade-leave-active {    //类名：显示到隐藏过程所需要的时间
 animation: bounce-in .5s reverse;   //reverse表示和隐藏到显示动画相反
}
@keyframes bounce-in {
 0% {
  transform: scale(0);
 }
 50% {
  transform: scale(1.5);
 }
 100% {
  transform: scale(1);
 }
}
</style>

<div>
 <button @click="show = !show">show toggle</button>
 <transition enter-class="fadeEnter" enter-active-class="fadeActive" > //fade 自定义名称
  <p v-if="show">hello</p>
 </transition>
</div>

<style>
.fadeActive{   
 transition: opacity .5s;   //类名：隐藏到显示过程所需要的时间
}
.fadeEnter {      // 类名:初始化状态
 opacity: 0;
}
</style>

// 在index.html文件下引入Animate.css
<link href="https://cdn.jsdelivr.net/npm/animate.css@3.5.1" rel="external nofollow" rel="stylesheet" type="text/css">
// 在组件内
<div>
 <button @click="show = !show">show toggle</button>
 <transition 
  enter-active-class="animated tada"
  leave-active-class="animated bounceOutRight" >
  <p v-if="show">hello</p>
 </transition>
</div>