react购物车

import React, { Component } from 'react';
 
import {Tabs} from './Tabs'
 
import 'whatwg-fetch'
 
import '../assets/css/Tab3.css'
import {Link} from 'react-router-dom'
 
 
export class Tab3 extends Component {
    constructor(props){
        super(props)
        this.state = {
            arr:[],
            totalPrice:0
        }
    }
    //获取输入框的值
    handInputChange=(e,i)=>{
        console.log(e.target.value)
        //文本框的值 e.target.value 需要赋值给 json 数据的下标为index
        this.setState({
            arr:this.state.arr.map((ele,index)=>{
                if(index==i){
                    ele.num=e.target.value
                    return ele
                }else {
                    return ele
                }
            })
        })
        this.SumPrice()
    }
    //add 加
    add=(e,i)=>{
        console.log(e.target.value)
        //文本框的值 e.target.value 需要赋值给 json 数据的下标为index
        this.setState({
            arr:this.state.arr.map((ele,index)=>{
                if(index==i){
                    ele.num=ele.num*1+1
                    return ele
                }else {
                    return ele
                }
            })
        })
        this.SumPrice()
 
    }
    //减
    jian=(e,i)=> {
        // console.log(e.target.value)
        //文本框的值 e.target.value 需要赋值给 json 数据的下标为index
        this.setState({
            arr: this.state.arr.map((ele, index) => {
                if (index == i) {
                    if(ele.num==0){
                        ele.num = 1
                        return ele
 
                    }else{
                        ele.num = ele.num*1-1
                        return ele
 
                    }
 
                } else {
                    return ele
                }
            })
        })
        this.SumPrice()
    }
    //删除
    del=(e,i)=>{
        this.setState({
            arr:this.state.arr.filter((ele,index)=>{
                if(index !=i ){
                    return true
                }
            })
        })
    }
    //获取单选框的值
    getCheckedChange=(e,i)=>{
        //console.log(e.target.checked)
        //文本框的值 e.target.value 需要赋值给 json 数据的下标为index
        this.setState({
            arr:this.state.arr.map((ele,index)=>{
                if(index==i){
                    ele.checked=e.target.checked
                    return ele
                }else {
                    return ele
                }
            })
        })
        this.SumPrice()
    }
    //点击全选和全不选
    CheckedChange=(e)=>{
        if(e.target.checked==true){
            this.setState({
                arr:this.state.arr.map((ele,index)=>{
                    ele.checked=true
                    return ele
                })
            })
 
        }else if(e.target.checked==false){
            this.setState({
                arr:this.state.arr.map((ele,index)=>{
                    ele.checked=false
                    return ele
                })
            })
        }
        this.SumPrice()
    }
    //计算总价
    SumPrice=()=>{
        var sum=0
        this.state.arr.forEach((ele,index)=>{
            sum+=ele.num*ele.new_price
        })
        this.setState({
            totalPrice:sum
        })
    }
    render() {
        // console.log(this.state.arr)
        return (
          <p className="shopCar">
 
            <p className='header'>
 
                <Link to="/tab1">返回</Link>
                <h3>购物车</h3>
 
            </p>
 
            <p className='section'>
                <p className='list'>
                    {
                        this.state.arr.map((ele,index)=>{
                            return (
                                <p className='item' key={index}>
 
                                            <p className='radio'>
                                                <input type="checkbox" checked={ele.checked} onChange={
                                                    (e)=>{
                                                        this.getCheckedChange(e,index)
                                                    }
                                                }/>
                                            </p>
 
                                            <p className='le'>
                                                <img src={ele.img} alt="" />
                                            </p>
 
                                            <p className='center'>
                                                <h3>{ele.name}</h3>
                                                <p className='num'>
                                                    <button onClick={(e)=>{
                                                        // console.log(e,index)
                                                        this.jian(e,index)
                                                    }}>-</button>
                                                    {/*获取文本框的值*/}
                                                    <input type="text" value={ele.num} onChange={(e)=>{
                                                        // console.log(e,index)
                                                        this.handInputChange(e,index)
                                                    }}/>
                                                    <button onClick={(e)=>{
                                                        // console.log(e,index)
                                                        this.add(e,index)
                                                    }}>+</button>
                                                </p>
 
                                                <p className="price">
                                                    <p>单价: {ele.new_price} 总价:{ele.new_price*ele.num}</p>
                                                </p>
 
                                            </p>
                                            <p className='ri'>
                                                <button onClick={(e)=>{
                                                    this.del(e,index)
                                                }}>删除</button>
                                            </p>
                                        </p>
                            )
                        })
                    }
                </p>
            </p>
 
            <p className="footer">
                            全选: <input type="checkbox" ref="quanxuan" onChange={
                (e)=>{
                    this.CheckedChange(e)
                }
                             }/>
                            合计: {this.state.totalPrice}
                            <button onClick={
                                (e)=>{
                                  this.props.history.push('/sub')
                                    //使用数组的过滤方法来选择更新之后的值
                                    var newArr=this.state.arr.filter((ele,index)=>{
                                        if(ele.checked==true){
                                            return true
                                        }else {
                                            return false
                                        }
                                    })
                                    //使用浏览器缓存来传递数据,因为h5
                                    window.localStorage.setItem("shuju",JSON.stringify(newArr))
                                }
                            }>结算</button>
                    </p>
 
          </p>
        );
    }
    //渲染页面
    componentDidMount(){
        var url = './shopping.json'
 
            fetch(url)
            .then((res)=>{return res.json()})
            .then((res)=>{
                this.setState({
                    arr:res
                })
            })
      }
    //页面更新
    componentDidUpdate(){
        // console.log("更新了")
        var bool=this.state.arr.every((ele,index)=>{
            if(ele.checked==true){
                return true
            }else {
                return false
            }
        })
        // console.log(bool)
        if(bool==true){
            this.refs.quanxuan.checked=true
        }else {
            this.refs.quanxuan.checked=false
        }
    }
 
 
 
}