How to implement the shopping cart function in WeChat applet? The following article will introduce to you how to implement the shopping cart function in WeChat applet. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Whether it is a shopping mall or catering applet, the transaction needs to be completed by placing an order, so there is an operation to add to the shopping cart. In the past, the shopping cart function was basically implemented through a large number of DOM operations. Since the applet is not based on the web, it cannot create a DOM. WeChat applet implements shopping cart functionIn fact, it is very similar to the usage of vue.js.

First, let’s figure out the needs of the shopping cart.

Single selection, all selection and cancellation, and the total price will be calculated according to the selected products

Increase and decrease of the purchase quantity of a single product

Delete products . When the shopping cart is empty, the page will change to the layout of the empty shopping cart

According to the design drawing, we can first implement a static page. Next, let’s look at what kind of data a shopping cart requires.

First is a product list (carts). The items in the list need: product image (image), product name (title), unit price (price), quantity (num), whether it is selected (selected), Product id (id)

Then select all in the lower left corner, a field (selectAllStatus) is required to indicate whether all are selected

The total price in the lower right corner (totalPrice)

Finally Need to know whether the shopping cart is empty (hasList)

Now that we need these data, we define these first when the page is initialized.

Initialization code:

Page({
    data: {
        carts:[],               // 購物車列表
        hasList:false,          // 列表是否有數(shù)據(jù)
       totalPrice:0,           // 總價，初始為0
       selectAllStatus:true    // 全選狀態(tài)，默認全選
    },
    onShow() {
        this.setData({
          hasList:true,        // 既然有數(shù)據(jù)了，那設為true吧
          carts:[
            {id:1,title:\'新鮮芹菜 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}
          ]
        });
      },
})

We usually get the shopping cart list data by requesting the server, so we put it in the life cycle function to assign values ??to carts. I thought about getting the latest status of the shopping cart every time I enter the shopping cart, and onLoad and onReady are only executed once during initialization, so I need to put the request in the onShow function.

Calculate the total price

Total price = Price of selected product 1 * Quantity Price of selected product 2 * Quantity …

According to the formula, we can get

getTotalPrice() {
    let carts =this.data.carts;                  // 獲取購物車列表
    let total = 0;
    for(let i = 0;i<carts.length; i++)="{        =" 循環(huán)列表得到每個數(shù)據(jù)<="span=" style=";padding: 0px">
        if(carts[i].selected){                   // 判斷選中才會計算價格
            total +=carts[i].num * carts[i].price;     // 所有價格加起來
        }
    }
    this.setData({                                // 最后賦值到data中渲染到頁面
        carts: carts,
        totalPrice:total.toFixed(2)
    });
}

This method needs to be called if other operations on the page will cause the total price to change.

Selection event

It is selected when clicked, and becomes unselected when clicked again. In fact, it is changing the selected field. Pass data-index="{{index}}" to pass the index of the current product in the list array to the event.

selectList(e) {
    const index =e.currentTarget.dataset.index;    // 獲取data- 傳進來的index
    let carts =this.data.carts;                    // 獲取購物車列表
    const selected =carts[index].selected;         // 獲取當前商品的選中狀態(tài)
    carts[index].selected= !selected;              // 改變狀態(tài)
    this.setData({
        carts: carts
    });
   this.getTotalPrice();                           // 重新獲取總價
}

Select all event

Select all is to change the selected quantity of each product according to the all-selected status selectAllStatus

selectAll(e) {
    let selectAllStatus =this.data.selectAllStatus;    // 是否全選狀態(tài)
    selectAllStatus =!selectAllStatus;
    let carts =this.data.carts;
 
    for (let i = 0; i< carts.length; i++) {
        carts[i].selected = selectAllStatus;            // 改變所有商品狀態(tài)
    }
    this.setData({
        selectAllStatus:selectAllStatus,
        carts: carts
    });
   this.getTotalPrice();                               // 重新獲取總價
}

Click on the number, add 1 to num, click on the - number, if num > 1, then subtract 1

// 增加數(shù)量
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();
},
// 減少數(shù)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();
}

Delete the product

Click the delete button to delete the current element from the shopping cart list. If the shopping cart is empty after deletion, change the shopping cart empty flag hasList to false

deleteList(e) {
    const index =e.currentTarget.dataset.index;
    let carts =this.data.carts;
   carts.splice(index,1);             // 刪除購物車列表里這個商品
    this.setData({
        carts: carts
    });
   if(!carts.length){                 // 如果購物車為空
        this.setData({
            hasList:false              // 修改標識為false，顯示購物車為空頁面
        });
    }else{                              // 如果不為空
       this.getTotalPrice();           //重新計算總價格
    }  
}

Mini program shopping cart function development splits each functional module into separate Development is basically the same as the web and APP development ideas. Although the shopping cart function is relatively simple, there are still many knowledge points involved in the WeChat applet.

Recommendation: " Mini Program Development Tutorial"

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