const root = document.getElementById("root");

function App() {
  const [counter, setCounter] = React.useState(0);
  const onClick = () => {
    //setCounter(counter + 1);
    setCounter((current) => current + 1); // 좀 더 안전하게 state 변경하기
  }
  return (
    <div>
      <h3>Total clicks: {counter}</h3>
      <button onClick={onClick}>Click me</button>
    </div>
  );
}
ReactDOM.render(<App />, root);