SOURCE

new Vue({
  el: '#app',
  data: {
    map: {
      a: 1
    },
    del:true
  },
  methods: {
    removeFromMap:function() {
      console.log( this.map.a);
      this.a=null;
      this.del = !this.del; 
    }
  }
});

<div id="app">
  <p v-show="del">
    {{map.a}}
  </p>
   <p v-if="null === map.a">
    {{map.a}}
  </p>
  <button v-on:click="removeFromMap">
    删除
  </button>
   <button v-on:click="removeFromMap">
    删除
  </button>
</div>