App.js

// App.js (parent component)
...
...
...
  // this function is NOT re-created on ever re-execution of this function
  const onDemoClick = useCallback(() => {
    console.log("Demo click function invoked");
  }, []);
  return (
    <div>
      <h2>Virtual DOM demo by Aditya Tyagi</h2>
     {/* the function onDemoClick will not be re-recreated every-time on re-exection of this parent. It will only be re-created when any of the params passed to dependency array changes. */}
      <DemoOutput onClick={onDemoClick} show={false} />
    </div>
  );