useStateimport React from "react";import ReactDOM from "react-dom";function App() { return ( Hello Start editing to see some magic happen! );};const rootElement = document.getElementById("root");ReactDOM.render(, rootElement);useState는 항상 2개의 value를 return첫번째 value를 item두번째 value는 값을 변경하게 함import React, {useState} from "react" // useState를 importconst [item, se..