How to handle scroll event properly

scroll_perf.js

function updatePage() {

  // do stuff

  scheduleAnimationFrame = false;
}

function onScroll() {
  lastScroll = window.scrollY;

  if (scheduleAnimationFrame)
    return;

  scheduleAnimationFrame = true;
  requestAnimationFrame(updatePage);
}

window.addEventListener('scroll', onScroll, false);