問題描述：

商品列表中只有“+”，點選之後出現“-1+”，可以對數量進行增減，

效果

.wxml

 <view class="add-box">         
       <image src="/image/reduce.png" class="add-img {{item.numbers==0 ?'none':''}}" bindtap="reduceNum" data-index="{{index}}"></image>
       <view  class="num {{item.numbers==0?'none':''}}"
 
>{{item.numbers}}</view>
       <image src="/image/add1.png" class="add-img" bindtap="addNum" data-index="{{index}}" data-index="{{index}}"></image>
 </view>

.js

數量是從後臺拿到的一個數據，每次點選“+”使得這個商品的數量自增一，點選“-”則數量自減一，直到數量為0後數量和減號消失

 data:{
     amount: 0,
    index:0,
 },


 addNum(e) {
    let index = e.currentTarget
 
.dataset.index;
    let fruitUrl = this.data.fruitUrl;
    let numbers = fruitUrl[index].numbers;
    numbers = numbers + 1;
    fruitUrl[index].numbers = numbers;
    this.setData({
      fruitUrl: fruitUrl
    });
  },

  reduceNum(e) {
    let index = e.currentTarget.dataset.index;
    let fruitUrl = this.data
 
.fruitUrl;
    let numbers = fruitUrl[index].numbers;
    numbers--;
    fruitUrl[index].numbers = numbers;

    this.setData({

      fruitUrl: fruitUrl
    })

    },