将变量从窗口全局加载到React应用程序不起作用

import React from 'react';

const MyContext = React.createContext();

import React from 'react';

const MyContext = React.createContext();

function App() {
  const myVariable = 'Hello World';

  return (
    <MyContext.Provider value={myVariable}>
      {/* 其他组件 */}
    </MyContext.Provider>
  );
}

export default App;

import React from 'react';

const MyContext = React.createContext();

function MyComponent() {
  return (
    <MyContext.Consumer>
      {value => <div>{value}</div>}
    </MyContext.Consumer>
  );
}

export default MyComponent;