微信小程序之购物车功能【黑马web前端】

Page({
    data: {
        carts:[],               // 购物车列表
        hasList:false,          // 列表是否有数据
        totalPrice:0,           // 总价，初始为0
        selectAllStatus:true    // 全选状态，默认全选
    },
    onShow() {
        this.setData({
          hasList: true,        // 既然有数据了，那设为true吧
          carts:[
            {id:1,title:'新鲜芹菜 半斤',image:'/image/s5.png',num:4,price:0.01,selected:true},
            {id:2,title:'素米 500g',image:'/image/s6.png',num:1,price:0.03,selected:true}
          ]
        });
      },
})

<view class="cart-box">
    <!-- wx:for 渲染购物车列表 -->
    <view wx:for="{{carts}}">
    
        <!-- wx:if 是否选择显示不同图标 -->
        <icon wx:if="{{item.selected}}" type="success" color="red" bindtap="selectList" data-index="{{index}}" />
        <icon wx:else type="circle" bindtap="selectList" data-index="{{index}}"/>
        
        <!-- 点击商品图片可跳转到商品详情 -->
        <navigator url="../details/details?id={{item.id}}">
            <image class="cart-thumb" src="{{item.image}}"></image>
        </navigator>
        
        <text>{{item.title}}</text>
        <text>￥{{item.price}}</text>
        
        <!-- 增加减少数量按钮 -->
        <view>
            <text bindtap="minusCount" data-index="{{index}}">-</text>
            <text>{{item.num}}</text>
            <text bindtap="addCount" data-index="{{index}}">+</text>
        </view>
        
        <!-- 删除按钮 -->
        <text bindtap="deleteList" data-index="{{index}}"> × </text>
    </view>
</view>

<view>
    <!-- wx:if 是否全选显示不同图标 -->
    <icon wx:if="{{selectAllStatus}}" type="success_circle" color="#fff" bindtap="selectAll"/>
    <icon wx:else type="circle" color="#fff" bindtap="selectAll"/>
    <text>全选</text>
    
    <!-- 总价 -->
    <text>￥{{totalPrice}}</text>
</view>

getTotalPrice() {
    let carts = this.data.carts;                  // 获取购物车列表
    let total = 0;
    for(let i = 0; i<carts.length; i++) {         // 循环列表得到每个数据
        if(carts[i].selected) {                   // 判断选中才会计算价格
            total += carts[i].num * carts[i].price;     // 所有价格加起来
        }
    }
    this.setData({                                // 最后赋值到data中渲染到页面
        carts: carts,
        totalPrice: total.toFixed(2)
    });
}

selectList(e) {
    const index = e.currentTarget.dataset.index;    // 获取data- 传进来的index
    let carts = this.data.carts;                    // 获取购物车列表
    const selected = carts[index].selected;         // 获取当前商品的选中状态
    carts[index].selected = !selected;              // 改变状态
    this.setData({
        carts: carts
    });
    this.getTotalPrice();                           // 重新获取总价
}

[mw_shl_code=html,true]selectAll(e) {
    let selectAllStatus = this.data.selectAllStatus;    // 是否全选状态
    selectAllStatus = !selectAllStatus;
    let carts = this.data.carts;
    for (let i = 0; i < carts.length; i++) {
        carts[i].selected = selectAllStatus;            // 改变所有商品状态
    }
    this.setData({
        selectAllStatus: selectAllStatus,
        carts: carts
    });
    this.getTotalPrice();                               // 重新获取总价
}

addCount(e) {
    const index = e.currentTarget.dataset.index;
    let carts = this.data.carts;
    let num = carts[index].num;
    num = num + 1;
    carts[index].num = num;
    this.setData({
      carts: carts
    });
    this.getTotalPrice();
},

// 减少数量
minusCount(e) {
    const index = e.currentTarget.dataset.index;
    let carts = this.data.carts;
    let num = carts[index].num;
    if(num <= 1){
      return false;
    }
    num = num - 1;
    carts[index].num = num;
    this.setData({
      carts: carts
    });
    this.getTotalPrice();
}