微信小程序实战篇-购物车

先上效果图

        

cart.wxml 

<import src="/template/quantity/index.wxml" />
<scroll-view class="scroll" scroll-y="true">
  <view class="separate"></view>
  <view wx:for="{
   
   {carts}}">
    <view class="cart_container">
      <image class="item-select" bindtap="switchSelect" data-index="{
   
   {index}}" data-id="{
   
   {index}}" src="{
   
   {item.isSelect?'../../images/cart/comment_select.png':'../../images/cart/comment_normal.png'}}" />

      <image class="item-image" src="{
   
   {item.pic}}"></image>

      <view class="column">
        <text class="title">{
   
   {item.name}}</text>
        <view class="row">
          <text class="sku-price">￥</text>
          <text class="sku-price">{
   
   {item.price}}</text>
          <view class="sku">
            <template is="quantity" data="{
   
   { ...item.count, componentId: index }}" />
          </view>
        </view>

      </view>
    </view>
    <view class="separate"></view>
  </view>
</scroll-view>
<view class="bottom_total">
  <view class="bottom_line"></view>

  <view class="row">
    <image class="item-allselect" bindtap="allSelect" src="{
   
   {isAllSelect?'../../images/cart/comment_select.png':'../../images/cart/comment_normal.png'}}" />
    <text class="small_text">全选</text>
    <text>合计:￥ </text>
    <text class="price">{
   
   {totalMoney}}</text>
    <button class="button-red" bindtap="toBuy" formType="submit">去结算</button>
  </view>
</view>

 布局不是很复杂，一个循环列表，循环出购物车商品，外加一个结算的底部控件，还需要提醒的是，循环列表外面要加一层scroll-view，这样当数据很多是时候，可以滚动，不熟悉scroll-view的，请自行翻看前面几篇文章，里面有讲解

cat.wxss 

/* pages/cart/cart.wxss */
.cart_container {
  display: flex;
  flex-direction: row;
}
.scroll {
  margin-bottom: 120rpx;
}
.column {
  display: flex;
  flex-direction: column;
}
.row {
  display: flex;
  flex-direction: row;
  align-items: center;
}
.sku {
  margin-top: 60rpx;
  margin-left: 100rpx;
}
.sku-price {
  color: red;
  position: relative;
  margin-top: 70rpx;
}
.price {
  color: red;
  position: relative;
}
.title {
  font-size: 38rpx;
  margin-top: 40rpx;
}
.small_text {
  font-size: 28rpx;
  margin-right: 40rpx;
  margin-left: 10rpx;
}
.item-select {
  width: 40rpx;
  height: 40rpx;
  margin-top: 90rpx;
  margin-left: 20rpx;
}
.item-allselect {
  width: 40rpx;
  height: 40rpx;
  margin-left: 20rpx;
}
.item-image {
  width: 180rpx;
  height: 180rpx;
  margin: 20rpx;
}
.bottom_line {
  width: 100%;
  height: 2rpx;
  background: lightgray;
}
.bottom_total {
  position: fixed;
  display: flex;
  flex-direction: column;
  bottom: 0;
  width: 100%;
  height: 120rpx;
  line-height: 120rpx;
  background: white;
}
.button-red {
  background-color: #f44336; /* 红色 */
}
button {
  position: fixed;
  right: 0;
  color: white;
  text-align: center;
  display: inline-block;
  font-size: 30rpx;
  border-radius: 0rpx;
  width: 30%;
  height: 120rpx;
  line-height: 120rpx;
}

 wxss样式没什么可说的，了解其属性，调用class就好，重点说一下cart.js,全篇的逻辑都在这里面

 cart.js 

// pages/cart/cart.js
var Temp = require('../../template/contract.js');
Page(Object.assign({}, Temp.Quantity, {
  data: {
    isAllSelect:false,
    totalMoney:0,
    // 商品详情介绍
    carts: [
      {
        pic: "http://mz.djmall.xmisp.cn/files/product/20161201/148058328876.jpg",
        name:"日本资生堂洗颜",
        price:200,
        isSelect:false,
        // 数据设定
        count: {
          quantity: 2,
          min: 1,
          max: 20
        },
      },
      {
        pic: 'http://mz.djmall.xmisp.cn/files/product/20161201/148058301941.jpg',
        name: "倩碧焕妍活力精华露",
        price: 340,
        isSelect: false,
        // 数据设定
        count: {
          quantity: 1,
          min: 1,
          max: 20
        },
      },
      {
        pic: 'http://mz.djmall.xmisp.cn/files/product/20161201/14805828016.jpg',
        name: "特效润肤露",
        price: 390,
        isSelect: false,
        // 数据设定
        count: {
          quantity: 3,
          min: 1,
          max: 20
        },
      },
      {
        pic: 'http://mz.djmall.xmisp.cn/files/product/20161201/148058228431.jpg',
        name: "倩碧水嫩保湿精华面霜",
        price: 490,
        isSelect: false,
        // 数据设定
        count: {
          quantity: 1,
          min: 1,
          max: 20
        },
      },
      {
        pic: 'http://mz.djmall.xmisp.cn/files/product/20161201/148057953326.jpg',
        name: "兰蔻清莹柔肤爽肤水",
        price: 289,
        isSelect: false,
        // 数据设定
        count: {
          quantity: 10,
          min: 1,
          max: 20
        },
      },
      {
        pic: "http://mz.djmall.xmisp.cn/files/product/20161201/148057921620_middle.jpg",
        name: "LANCOME兰蔻小黑瓶精华",
        price: 230,
        isSelect: false,
        // 数据设定
        count: {
          quantity: 1,
          min: 1,
          max: 20
        },
      },
    ],
  },
 
  //勾选事件处理函数  
  switchSelect: function (e) {
    // 获取item项的id，和数组的下标值  
    var Allprice = 0,i=0;
    let id = e.target.dataset.id,
  
    index = parseInt(e.target.dataset.index);
    this.data.carts[index].isSelect = !this.data.carts[index].isSelect;
    //价钱统计
    if (this.data.carts[index].isSelect) {
      this.data.totalMoney = this.data.totalMoney + this.data.carts[index].price;
    }
    else {
      this.data.totalMoney = this.data.totalMoney - this.data.carts[index].price;
    }
   //是否全选判断
    for (i = 0; i < this.data.carts.length; i++) {
      Allprice = Allprice + this.data.carts[i].price;
    }
    if (Allprice == this.data.totalMoney)
    {
      this.data.isAllSelect=true;
    }
    else 
    {
      this.data.isAllSelect = false;
    }
    this.setData({
      carts: this.data.carts,
      totalMoney: this.data.totalMoney,
      isAllSelect: this.data.isAllSelect,
    })
  },
  //全选
  allSelect: function (e) {
    //处理全选逻辑
    let i = 0;
    if (!this.data.isAllSelect)
    {
      for (i = 0; i < this.data.carts.length; i++) {
        this.data.carts[i].isSelect = true;
        this.data.totalMoney = this.data.totalMoney + this.data.carts[i].price;
      }
    }
    else
    {
      for (i = 0; i < this.data.carts.length; i++) {
        this.data.carts[i].isSelect = false;
      }
      this.data.totalMoney=0;
    }
    this.setData({
      carts: this.data.carts,
      isAllSelect: !this.data.isAllSelect,
      totalMoney: this.data.totalMoney,
    })
  },
  // 去结算
  toBuy() {
    wx.showToast({
      title: '去结算',
      icon: 'success',
      duration: 3000
    });
    this.setData({
      showDialog: !this.data.showDialog
    });
  },
  //数量变化处理
  handleQuantityChange(e) {
    var componentId = e.componentId;
    var quantity = e.quantity;
    this.data.carts[componentId].count.quantity = quantity;
    this.setData({
      carts: this.data.carts,
    });
  }
}));

---

介绍一下用到的参数

• isAllSelect：是否全选
• totalMoney：总金额
• carts ：购物车商品数据

switchSelect 勾选按钮需要做的逻辑处理

• 判断是否达到全部勾选，如果全部勾选，底部的全选按钮要点亮，判断依据是，价钱是否等于总价，当然这只是一种判断方式，读者也可以通过勾选的数量判断，
• 对勾选或取消的按钮，进行总价的加减法计算
• this.setData，更新数据，这个是重点，每次处理完数据，都要记得更新数据

allSelect 全选按钮的逻辑处理

• 全选就把每个item勾选图标点亮，然后统计总价钱，不全选就置为灰色，总价钱为0
• this.setData更新数据

  ---

  微信小程序数据处理

一、修改数据方式 

1. this.data.name 

2. this.setData 

这两种方式都可以改变数据，this.setData的好处是可以有刷新的效果，即实时更新数据 

二、修改对象数组 

1. 修改全部对象 

2. 修改部分数据 

三、添加删除数据 

1. 添加数据concat 

//假设这一段是我们要新增的数组
var newarray = [{
        name:'增加的数据--'+new Date().getTime() ,
}];
//向前--用newarray与this.data.list合拼
this.data.list = newarray.concat(this.data.list);
//向后--用this.data.list与newarray合拼
this.data.list = this.data.list.concat(newarray);

 2. 删除数据**splice()**删除数据，然后返回被删除的数据

//删除
  remove:function (e){
    var dataset = e.target.dataset;
    var Index = dataset.index;
    //通过index识别要删除第几条数据，第二个数据为要删除的项目数量，通常为1
    this.data.list.splice(Index,1);
    //渲染数据
    this.setData({
        list:this.data.list
    });
  }

 3. 清空数据

//清空
  clear:function (){
    //其实就是让数组变成一个空数组即可
      this.setData({
          list:{}
      });
  }