SOURCE

  new Vue({
  	el:'#app',
    data:{
    	num:4
    },
    methods:{
    	add(){ 
      	this.num++;  
      }
    }
  })

<div id="app">
  <div class='head'>
    <span class='num'>{{num}}</span>
   <input type="button" @click='add()' value="+">
  </div>
  <div class='goodslist' v-for="(item,index) in num"> 
     <div>
       <span>兑换码</span>
       <input type="text" />
     </div>
  </div>
</div>

#app{
  padding:50px;
}
.head{
  padding-bottom:20px;
}
.num{
  color:yellow;
  margin-right:10px;
}