clark-firefox-helper.js

/*
 * Firefox super responsive scroll (c) Keith Clark - MIT Licensed
 */
(function(doc)
{
	var root = doc.documentElement,
		scrollbarWidth, scrollEvent;

	// Not ideal, but better than UA sniffing.
	if ("MozAppearance" in root.style) {

		// determine the vertical scrollbar width
		scrollbarWidth = root.clientWidth;
		root.style.overflow = "scroll";
		scrollbarWidth -= root.clientWidth;
		root.style.overflow = "";

		// create a synthetic scroll event
		scrollEvent = doc.createEvent("UIEvent")
		scrollEvent.initEvent("scroll", true, true);

		// event dispatcher
		function scrollHandler() {
			doc.dispatchEvent(scrollEvent);
		}

		// detect mouse events in the document scrollbar track
		doc.addEventListener("mousedown", function(e) {
		if (e.clientX > root.clientWidth - scrollbarWidth) {
			doc.addEventListener("mousemove", scrollHandler, false);
			doc.addEventListener("mouseup", function() {
			doc.removeEventListener("mouseup", arguments.callee, false);
			doc.removeEventListener("mousemove", scrollHandler, false);
			}, false)
		}
		}, false)

		// override mouse wheel behaviour.
		doc.addEventListener("DOMMouseScroll", function(e) {
		// Don't disable hot key behaviours
		if (!e.ctrlKey && !e.shiftKey) {
			root.scrollTop += e.detail * 16;
			scrollHandler.call(this, e);
			e.preventDefault()
		}
		}, false)

	}
})(document);