javascript_scroll_event.js

function MouseWheelHandler(e) {
  var e = window.event || e; // old IE support
  var delta = Math.max(-1, Math.min(1, (e.wheelDelta || -e.detail)));
  if (delta < 0) // scroll down
    // scroll downaction here
  else // scroll up
    // scroll up action here
}

if (window.addEventListener) {
  window.addEventListener("mousewheel", MouseWheelHandler, false);
  window.addEventListener("DOMMouseScroll", MouseWheelHandler, false);
}