vue2.0 transition规范写法

html

 <div id="demo">
  <button v-on:click="show = !show">
    Toggle
  </button>
  <transition name="fade">
    <p v-if="show">hello</p>
  </transition>
</div>

js

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

css

.fade-enter-active, .fade-leave-active {
  transition: opacity .5s
}
.fade-enter, .fade-leave-active {
  opacity: 0
}