React `useEffect`

useEffect.js

function App() {
  let divRef = useRef(null);

  useEffect(() => {
    var text = document.createTextNode(" Rendered ");
    divRef.current.appendChild(text);
    return () => {
      var text = document.createTextNode(" Unrendered ");
      divRef.current.appendChild(text);
    };
  });

  useEffect(() => {
    var text = document.createTextNode(" Mounted ");
    divRef.current.appendChild(text);
    return () => {
      var text = document.createTextNode(" Unmounted ");
      divRef.current.appendChild(text);
    };
  }, []);

  return (
    <div className="App" ref={divRef}>
    </div>
  );
}