StrictMode क्या करता है

import { StrictMode } from 'react';
import { createRoot } from 'react-dom/client';

createRoot(document.getElementById('root')).render(
  <StrictMode>
    <App />
  </StrictMode>
);

useEffect(() => {
  const id = setInterval(() => setTick(t => t + 1), 1000);
  return () => clearInterval(id); // cleanup required!
}, []);

function App() {
  return (
    <>
      <LegacyPart />  {/* not wrapped */}
      <StrictMode>
        <NewFeature />
      </StrictMode>
    </>
  );
}