<div id="box">
    <input type="button" value="按钮" @click="toggle">
    <div id="div1" v-show="isShow"></div>
  </div>
  <script type="text/javascript">
    var vm = new Vue({
      el:'#box',
      data:{
        isShow:false
      },
      methods:{
        toggle(){
          this.isShow = !this.isShow;
        }
      }
    });
  </script>

  <div id="box">
    <input type="button" value="按钮" @click="toggle">
    <transition name="fade">
      <div id="div1" v-show="isShow" transiton="fade"></div>
    </transition>
  </div>
    .fade-enter-active, .fade-leave-active {
     transition: opacity .5s
    }
    .fade-enter, .fade-leave-active {
     opacity: 0
    }