"dependencies": { "next": "10.0.3", "react": "17.0.1", "react-dom": "17.0.1", }, type ChildProps = { count: number; }; const Child = ({ count }: ChildProps): JSX.Element => { useEffect(() => { console.log("Childがレンダリングされたよ"); }); return <p>Child:{count}</p>; }; const Parent: NextPage = () => { const [parentCount, setParentCount] = useState<number>(0); const [childCount, setChildCount] = useState<n