vue 상태 과도 transition 이 작용 하지 않 는 원인 해결

<transition name="fade">
   <div v-if="show" key="box1">
     <div class="item-box"></div>
   </div>
   <div v-else key="box2">
     <span>    </span>
   </div>
</transition>

<transition :name="slide">
 <keep-alive>
  <component 
   :is="questionMap[currentQuestion.type]"
   :key="index"
   :currentQuestion="currentQuestion"
   :index="index">
  </component>
 </keep-alive>
</transition>

<transition :name="slide" mode="out-in">
 <keep-alive>
  <component 
   :is="questionMap[currentQuestion.type]"
   :key="index"
   :currentQuestion="currentQuestion"
   :index="index">
  </component>
 </keep-alive>
</transition>

<div id="list-demo" class="demo">
 <button v-on:click="add">Add</button>
 <button v-on:click="remove">Remove</button>
 <transition-group name="list" tag="p">
  <span v-for="item in items" v-bind:key="item" class="list-item">
   {{ item }}
  </span>
 </transition-group>
</div>

new Vue({
 el: '#list-demo',
 data: {
  items: [1,2,3,4,5,6,7,8,9],
  nextNum: 10
 },
 methods: {
  randomIndex: function () {
   return Math.floor(Math.random() * this.items.length)
  },
  add: function () {
   this.items.splice(this.randomIndex(), 0, this.nextNum++)
  },
  remove: function () {
   this.items.splice(this.randomIndex(), 1)
  },
 }
})

.list-item {
 display: inline-block;
 margin-right: 10px;
}
.list-enter-active, .list-leave-active {
 transition: all 1s;
}
.list-enter, .list-leave-to
/* .list-leave-active for below version 2.1.8 */ {
 opacity: 0;
 transform: translateY(30px);
}