January 14, 2021

// See https://developer.mozilla.org/en-US/docs/Web/Events/scroll

var lastScrollPosition = 0,
    tick = false;  // Track whether call is currently in process

function customFunction (scrollPos) {
  // Custom function that does something
  // based on the scroll position
}

window.addEventListener('scroll', function(e) {
  lastScrollPosition = window.scrollY;
  if (!tick) {
    setTimeout(function () {
      customFunction(lastScrollPosition);
      tick = false;
    }, 16)
  }
  tick = true;
});