index.js

import React from 'react'
import ReactDOM from 'react-dom'
import CartSimple from './CartSimple'

 const jsx = (
  <div>
  <h1>React Study</h1>
  <CartSimple/>
</div>
 );
 //渲染组件
ReactDOM.render(jsx,document.getElementById("root"));

CartSimple组件

import React, { Component } from 'react'

function CartByMe(props) {
    return (
        <table>
            <tbody>
                {
                 props.cart.map((goods, i) => {
                            return (<tr key={i}>
                                <td >名称：{goods.tital} </td>
                                <td >总价格：{goods.price * goods.count} </td>
                            </tr>)
                        })

                }
            </tbody>
        </table>
    )
}
export default class CartSimple extends Component {

    constructor(props) {
        super(props)

        this.state = {
            goods: [],
            price: "",
            tital: '',
            cart: []
        }
    }
    componentDidMount() {
        //发起请求
        setTimeout(() => {
            let goods = [
                { id: 1, tital: "React入门", price: 100 },
                { id: 2, tital: "React高级", price: 800 },
                { id: 3, tital: "React进阶", price: 600 },
                { id: 4, tital: "React精通", price: 200 },
            ];
            this.setState({
                goods
            })
        }, 1000);
    }
    handlePrice = e => {

        this.setState(
            {
                price: e.target.value
            }
        );
    }
    handleTital = (e) => {
        this.setState({
            tital: e.target.value
        })
    }
    addNewGood = (e) => {
        if (this.state.tital && this.state.price) {
            let lenMax = this.state.goods.length;
            this.setState({
                goods: [...this.state.goods, { id: lenMax + 1, tital: this.state.tital, price: this.state.price }]
            })
        }

    }
    addShop = (id) => {
        const goods = this.state.goods.map((item) => {
            if(item.id == id){
                return item;
            }
        });
        const good = goods.filter((item)=>{
            if(item!=null){
                return item;
            }
        })

        const cartGoods = this.state.cart.find(v => v.tital === good[0].tital);
        if (cartGoods) {
            //已经在购物侧里面有了
            const newCart = [...this.state.cart];
            newCart.forEach((item) => {
                if (item.id == id) {
                    item.count += 1;
                }
            })
            this.setState({
                cart: newCart
            })

        } else {
            //第一次添加商品

            this.setState({
                cart: [...this.state.cart, {
                    active: true,
                    id: good[0].id,
                    tital: good[0].tital,
                    price: good[0].price,
                    count: 1
                }]
            })
        }

    }
    render() {
        return (
            <div>
                <h1>购物侧</h1>
                <div>
                    <p>
                        <label htmlFor="tital">名字</label>
                        <input type="text" id="tital" value={this.state.tital} onChange={this.handleTital} />
                    </p>
                    <p>
                        <label htmlFor="price">价格</label>
                        <input type="text" id="price" value={this.state.price} onChange={this.handlePrice} />
                    </p>

                    <button onClick={this.addNewGood} value="添加">添加</button>
                </div>
                <ul>
                    {
                        this.state.goods.map((item) => {
                            return (
                                <li key={item.id}>
                                    <span>名称:{item.tital}</span>
                                    <span>价格：{item.price}</span>
                                    <button onClick={() => this.addShop(item.id)} value="">添加购物侧</button>
                                </li>);
                        })
                    }
                </ul>
                <hr></hr>
                <CartByMe cart={this.state.cart}></CartByMe>
            </div>
        )
    }
}

效果图