react的Provider,Consumer


import React from 'react'
import ReactDOM from "react-dom"
const {Provider,Consumer} = React.createContext()
class ContextDemo extends React.Component {
  state={
      newContext:'createContext'
  }
  render() {
    const {newContext} = this.state
    return (
        <Provider value={newContext}>
            <div>
                <label>childContent</label>
                <input type="text" value={newContext} onChange={e=>this.setState({newContext:e.target.value})}/>
            </div>
            <Son />
        </Provider>
    )
  }
}
class Son extends React.Component{
    render(){
        return <Consumer>
            {
                (name)=>
                    <div style={{border:'1px solid red',width:'60%',margin:'20px auto',textAlign:'center'}}>
                        <p>子组件获取到的内容:{name}</p>
                        <Grandson />
                    </div>
                
            }
        
        </Consumer>
    }
}
class Grandson extends React.Component{
    render(){
        return <Consumer>
            {
                (name)=>
                    <div style={{border:'1px solid red',width:'60%',margin:'20px auto',textAlign:'center'}}>
                        <p>孙子组件获取到的内容:{name}</p>
                    </div>
                
            }
        </Consumer>
    }
}


function render(){
  ReactDOM.render(
    <ContextDemo/>,
    document.getElementById('root')
  );
}

render();


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