Detailed explanation of the use of React list bar and shopping cart components

import React from 'react';
import axios from 'axios';
import GoBack from '../smallPage/GoBack';
import '../../Assets/css/storeDetail.css';
import MenuList from '../../Mock/MenuList';
import Order from '../menuPage/Order';
import Evaluate from '../menuPage/Evaluate';
import Business from '../menuPage/Business';

class StoreDetail extends React.Component {
    constructor(props) {
        super(props);
        this.state = {  
            food:null,
            menulist:MenuList
        };
    }
    componentDidMount(){
        axios.get("/food").then((res)=>{
            this.setState({
                food:res.data.result.data
            });
            console.log(this.state.food);
        });
    }
    userSelect=(index)=>{
        MenuList.forEach((val,key)=>{
            val.isshow=false;
            if(key===index){
                val.isshow=true;
            }
        });
        this.setState({
            menulist:MenuList
        });
    }
    render() {
        return (
            this.state.food?
                <div>
                    <GoBack title={this.state.food.poi_info.name}/>
                    <div className="foodimage">
                        <img src={this.state.food.poi_info.pic_url} alt=""/>
                        <img src={this.state.food.poi_info.head_pic_url} alt=""/>
                        <span>{this.state.food.poi_info.name}</span>
                    </div>
                    <div>
                        <ul className="menulist">
                            {
                                this.state.menulist.map((value,index)=>{
                                    return (
                                        <li key={index} onClick={this.userSelect.bind(this,index)}>
                                            {value.title}
                                            <span className={value.isshow?'foodline':''}></span>
                                        </li>
                                    )
                                })
                            }
                        </ul>
                    </div>
                    {
                        this.state.menulist.map((value,index)=>{
                            if(value.isshow&&index===0){
                                return <Order toprice={this.state.food.poi_info.shipping_fee_tip} orderlist={this.state.food.food_spu_tags} key={index}/>
                            }else if(value.isshow&&index===1){
                                return <Evaluate key={index}/>
                            }else if(value.isshow&&index===2){
                                return <Business key={index}/>
                            }else{
                                return '';
                            }
                        })
                    }
                </div>
            :''
        );
    }
}

export default StoreDetail;

import React from 'react';
import '../../Assets/css/order.css';
import AddCut from '../smallPage/AddCut';
import Cart from '../smallPage/Cart';

class Order extends React.Component {
    constructor(props) {
        super(props);
        this.state = {  
            list:[],
            leftindex:0
        };
    }
    scrollRight=(e)=>{
        let scrolltop=e.target.scrollTop;
        let listheight=this.state.list;
        for(let i=0;i<listheight.length-1;i++){
            if(scrolltop<listheight[i]){
                // When sliding, take the first set in the array and modify the index value this.setState({
                    leftindex:i
                });
                break;
            }else if(scrolltop>=listheight[i]&&scrolltop<listheight[i+1]){
                // When the right sliding value is greater than half of the total height, the left index needs to go down if (i+1>=listheight.length/2) {
                    // Get the ul on the left and move its scrollTop down this.refs.leftul.scrollTop=listheight[i+1];
                }else{
                    // Move the scrollTop upwards this.refs.leftul.scrollTop=0;
                }
                this.setState({
                    leftindex:i+1
                });
                break;
            }
        }
    }
    // When the user clicks, change the color of the current index userClick=(index)=>{
        this.setState({
            leftindex:index
        });
        this.refs.order_scroll.scrollTop=index-1>=0?this.state.list[index-1]:0;
    }
    componentDidMount(){
        let order_block = document.getElementsByClassName("order_block");
        let listinfo=this.state.list;
        // Loop through the divs, get the offset of each div, and then push it into this.state to modify and display it. After modification, get listinfo
        // If it is the first div, only take its own offset; otherwise, take its own offset + listinfo[i-1] for(let i=0;i<order_block.length;i++){
            if(i===0){
                listinfo.push(order_block[i].offsetHeight);
            }else{
                listinfo.push(order_block[i].offsetHeight+listinfo[i-1]);
            }
        }
        this.setState({
            list:listinfo
        });
        // console.log(listinfo); (11) [550, 612, 1284, 1712, 2628, 5496, 7083, 8609, 9099, 9465, 10747]
    }
    //Call the forced refresh method in the child component Cart, and execute the method in the AddCut component refComponent=()=>{
        let ele = this.refs.cart;
        ele.update();
    }
    render() {
        return (
            <div className="order">
                <div className="order_left">
                    <ul ref="leftul">
                        {
                            this.props.orderlist.map((value,index)=>{
                                return (
                                    // Determine the color of the left li according to the index<li onClick={this.userClick.bind(this,index)} className={this.state.leftindex===index?'leftli leftli_color':'leftli'} key={index}>
                                        <img src={value.icon} alt=""/>
                                        <span>{value.name}</span>
                                    </li>
                                )
                            })
                        }
                    </ul>
                </div>
                <div onScroll={this.scrollRight} className="order_right">
                    <div ref="order_scroll" className="order_scroll">
                        {
                            this.props.orderlist.map((value,index)=>{
                                return (
                                    <div className="order_block" key={index}>
                                        <ul>
                                            {
                                                value.spus.map((v,k)=>{
                                                    return (
                                                        <li key={k}>
                                                            <div className="order_block_img">
                                                                <img src={v.picture} alt=""/>
                                                            </div>
                                                            <div className="order_block_word">
                                                                <div className="order_block_word_name">{v.name}</div>
                                                                <div className="order_block_word_zan">{v.praise_content}</div>
                                                                <div className="order_block_word_price">
                                                                    <span>￥{v.min_price}</span>/piece<AddCut parent={this} name={v.name} price={v.min_price}/>
                                                                </div>
                                                            </div>
                                                        </li>
                                                    )
                                                })
                                            }
                                        </ul>
                                    </div>
                                )
                            })
                        }
                    </div>
                </div>
                <Cart ref="cart" toprice={this.props.toprice}/>
            </div>
        );
    }
}

export default Order;

import React from 'react';
import '../../Assets/css/addCut.css';
import CartData from '../../Mock/CartData';

class AddCut extends React.Component {
    constructor(props) {
        super(props);
        this.state = {  
            num:0
        };
    }
    userAdd=()=>{
        let addnum=this.state.num;
        addnum++;
        this.setState({
            num:addnum
        });
        this.addCart(addnum);
        this.props.parent.refComponent();
    }
    userCut=()=>{
        let cutnum=this.state.num;
        cutnum--;
        if(cutnum<0){
            cutnum=0;
        }
        this.setState({
            num:cutnum
        });
        this.addCart(cutnum);
        this.props.parent.refComponent();
    }
    addCart=(num)=>{
        // Generate an object collection let list={
            name:this.props.name,
            price:this.props.price,
            num:num
        };
        let same=false;
        if(CartData.length===0){
            CartData.push(list);
        }
        for(let i=0;i<CartData.length;i++){
            if(CartData[i].name===this.props.name){
                CartData[i].num=num;
                same=true;
            }
        }
        if(!same){
            CartData.push(list);
        }
    }
    render() {
        return (
            <div className="addcut">
                <img onClick={this.userCut} className={this.state.num>0?'show':'showhidden'} src={require("../../Assets/image/minus.edae56b865f90527f2657782f67d9c3e.png")} alt=""/>
                <span className={this.state.num>0?'show':'showhidden'}>{this.state.num}</span>
                <img onClick={this.userAdd} src={require("../../Assets/image/plus.af10af5a9cee233c612b3cff5c2d70cd.png")} alt=""/>
            </div>
        );
    }
}

export default AddCut;

import React from 'react';
import '../../Assets/css/cart.css';
import CartData from '../../Mock/CartData';

class Cart extends React.Component {
    constructor(props) {
        super(props);
        this.state = {  
            cart:[],
            totalprice:0
        };
    }
    update=()=>{
        // Read data this.setState({
            cart:CartData
        });
        // Calculate the total price let prices=0;
        for(let i=0;i<CartData.length;i++){
            prices+=CartData[i].price*CartData[i].num;
        }
        this.setState({
            totalprice:prices
        });
    }
    render() {
        return (
            <div className="cart">
                <div className="cart_left">
                    <img src={require("../../Assets/image/shop-icon.3a615332a0e634909dc3aa3a50335c8f.png")} alt=""/>
                    <span>￥{this.state.totalprice}</span><br/>
                    <span>{this.props.toprice} is also required</span>
                </div>
                <div className="cart_right">Go to checkout</div>
            </div>
        );
    }
}

export default Cart;