4、react 父子组件传值

父传子：


 3 父组件代码：
 4 import React from 'react';
 5 import User from './pages/User'
 6 import Search from './pages/Search'
 7 
 8 function App() {
 9  
10   const context = {
11     userInfo:'小明'
12   }
13 
14   return (
15     <div className="App">
16     <User context={context}/>
17     <Search context={context}/>
18     </div>
19   );
20 }
21 
22 export default App;
23 
24 函数子组件代码：
26 import React,{ useState,useEffect } from 'react'
28 function User(props){
30     const { userInfo } = props.context;
31     
32     return(
33         <React.Fragment>
34         <h1>function{userInfo}</h1>
35         </React.Fragment>
36     )
37 }
38 
39 export default User;

class子组件代码：

父组件：

import React from 'react';
import './App.css';
import Search from './pages/Search';


function tellme(msg){
  console.log(msg);
}

function App() { 
  const context = {
    userInfo:'小明'
  }

  return (
    <div className="App">
    <Search context={context}  tellme={tellme}/>
    </div>
  );
}

export default App;


子组件：

import React,{Component} from 'react'

class Search extends Component{
    constructor(props){
        super(props)
        this.state={
            data:'',
            str:''
        }
    }
    
   
        render() {
            const {data,str}= this.state;
           
            return(
                <React.Fragment>
                <button onClick={this.click}>点击</button><input type="text" name="" id="" value={data} onChange={this.Value}/>
                </React.Fragment>
            )
        }
        
        click=()=>{
            const {tellme}= this.props;
            tellme('我是Search');
            console.log(11);
        };
        Value=(e)=>{
            console.log(e.target.value);
            let val = e.target.value
            this.setState({
                data:val
            })
        }
    }

export default Search;