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案例：现在有个父-子-孙组件 需要进行组件通信

import { useState } from "react";
// 创建上下文
const CountContext = React.createContext();

//子组件
const SonComponent = (props) => {
  return (
    <div>
      <h2>子组件</h2>
      <GrandsonComponent></GrandsonComponent>
    </div>
  );
};
 

//孙组件
const GrandsonComponent= ({onGetMsg,count}) => {
  const msg=count===0?'999':0
  return (
    <div>
     <h3>孙组件</h3>
    </div>
  );
};



function App() {
   const title="hello world";
   
  const [count,setCount]=useState(0);
  return (
    <div className="App">
      <h1>父组件</h1>
      <SonComponent/>
    </div>
  );
}

export default App;

跨组件通信Context

import { useState,useContext ,createContext } from "react";
const CountContext = createContext();

//子组件
const SonComponent = (props) => {
  return (
    <div>
      <h2>子组件</h2>
      <GrandsonComponent></GrandsonComponent>
    </div>
  );
};
 

//孙组件
const GrandsonComponent = () => {
  const { count, setCount ,otherMsg} = useContext(CountContext);
  const msg = count === 0 ? '999' : 0;
  return (
    <div>
      <h3>孙组件{count}</h3>
      <button onClick={() => setCount(msg)}>{otherMsg}</button>
    </div>
  );
};



function App() {
    
  const [count,setCount]=useState(0);
  const otherMsg='父组件的参数'
  return (
    <CountContext.Provider value={{ count, setCount,otherMsg }}>
      <div className="App">
        <h1>父组件 {count}</h1>
        <SonComponent />
      </div>
    </CountContext.Provider>
  );
}

export default App;

也是就可以实现跨组件通讯，爷爷传参或方法给孙子，孙子获得参数调用和方法了