vue2 transition between two div elements

Question

I found that the transition doesn't work between two div elements as following:

<transition name="fade">
  <div v-if="show">111</div>
  <div v-else>222</div>
</transition>

but it works if there is only one div element like:

<transition name="fade">
  <div v-if="show">111</div>
  <p v-else>222</p>
</transition>

is that a vue 2 bug ? or I just can't use it with two div elements?

How to do it with two div elements ..?

Answer 1

You should add unique key attribute to divs in order to make it work: https://jsfiddle.net/a8fv6rvp/1/

<script src="https://unpkg.com/vue/dist/vue.js"></script>

<div id="app">
  <transition name="fade" mode="out-in">
    <div v-if="show" key="1">111</div>
    <div v-else key="2">222</div>
  </transition>
  <button @click="show = !show">Toggle</button>
</div>

new Vue({
    el: '#app',
  data: {
    show: true
  }
});

<style>
.fade-enter-active, .fade-leave-active {
  transition: opacity .5s
}
.fade-enter, .fade-leave-to {
  opacity: 0
}
</style>