CODE EXAMPLE FOR JAVASCRIPT

event listener for functional component

import React, { useEffect } from 'react';

const Component = (props) => {  
  useEffect(() => {
    window.addEventListener('scroll', handleScroll);
  });
  useEffect(() => {
    return () => {
      window.removeEventListener('scroll', handleScroll);
    };
  }, []);

  function handleScroll() {
    let scrollTop = window.scrollY;
  }


  return ()
}