react 父组件与子组件之间的值传递的方法

import React, { Component } from 'react'

export default class Item extends Component {
 constructor(props) {
  super(props)

  this.state = {
   prices: 0
  }
 }

 handleChange(){
  const prices =800;
  this.setState({
   prices: price
  })
  //用传过来的changePrice属性(props)，是个函数，呼叫它把price交给父组件中的函数去处理
  this.props.changePrice(price)
 }

 render() {
  const { prices } = this.state;
    return (
     <div>
       <div onChange={this.handleChange.bind(this)}>
       </div>
       <p>{prices}</p>
     </div>
    )
 }
}

import React, { Component } from 'react';
import Item from './Item'

class App extends Component {
 constructor(props) {
  super(props)

  this.state = {price: 0}
 }
 
 //给子组件用来传price用的方法
 changePrice(price){
  this.setState({price: price})
 }

 render() {
  return (
   <div>
    <Item changePrice={this.changePrice.bind(this)}/>
    <p>{this.state.price}</p>
   </div>
  );
 }
}

export default App;