const App = () => {
  const num = 1;
  
  
  const total = React.useMemo(() => {
    console.log('useMemo')
    return num * 2
  });
  
  const add = () => {
    console.log('methods');
    return num * 2;
  }
  
  return (
    <div>
      <p>useMemo：{ total }</p>
      <p>useMemo：{ total }</p>
      <p>useMemo：{ total }</p>
      <p>useMemo：{ total }</p>
      <p>useMemo：{ total }</p>
      
      <p>methods：{ add() }</p>
      <p>methods：{ add() }</p>
      <p>methods：{ add() }</p>
      <p>methods：{ add() }</p>
      <p>methods：{ add() }</p>
    </div>
  )
}
const root = ReactDOM.createRoot(document.querySelector('#root'));
root.render(<App />);