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                <div id="root"></div>




// Contextを生成する
const NumberContext = React.createContext();
// 2つの値を持つオブジェクトを返す
// { Provider, Consumer }

const App = () => {
  // Providerを活用して値を全ての
  // 子要素と孫要素に利用可能にする
  return (
    <NumberContext.Provider value={42}>
        <Display />

const Display = () => {
  // Consumerを活用してcontextから取得した値を使う
  // このコンポーネントはpropsを取らないことに注意!
  return (
      {value => <div>親コンポーネントから渡された値: {value}</div>}

ReactDOM.render(<App />, document.getElementById("root"));