react父子组件传值

1.父组件向子组件传值使用props

import React,{Component} from 'react'
import Center from './components/Center'

export default  class App extends Component {
  state={
    todos:[
      {id:'001',name:'吃饭',done:true},
      {id:'002',name:'睡觉',done:true},
      {id:'003',name:'打代码',done:false},
    ]
  }
 
  render(){
    return (
      

         
      
      
    ); 
  }
  
}

子组件接收，渲染页面

import React, { Component } from 'react'
import Center from './index.module.css'
export default class index extends Component {
  render() {
    let {todos} =this.props;
    return (
      

        

                {todos.map((i)=>{
                    return (
                        

                            

                                
                                {i.name}
                            
                            删除
                        
                    )
                })}
        
      
    )
    
  }
}

2.子组件向父组件传递参数

import React,{Component} from 'react'
// import Hello from './components/Hello'
import Header from './components/Header'
import Center from './components/Center'
import Foot from './components/Foot'

export default  class App extends Component {
  
  // ，data是子组件传给父组件的值
    a=(data)=>{
      console.log(data,'app')
    }
  render(){
    return (
      

        

         
      
      
    ); 
  }
  
}

子组件通过父组件传过来的函数，在合适的时机传给，父元素函数接收的data上

import React, { Component } from 'react'
import Header from './index.module.css'
export default class index extends Component {
  render() {
    return (
      

        
      
    )
  }
  // 回车响应
  keyCode=(e)=>{
    if(e.keyCode===13){
      this.props.a(e.target.value)
    }
  }
}