jQuery plugin to raise custom scroll_vertical and scroll_horizontal events

jquery-trackScroll.js

/**
 * Simple plugin to track scroll events and trigger a custom jQuery event (scroll_vertical or scroll_horizontal)
 * when the corresponding type of scroll has happened.
 * Event handlers can receive the original scroll event and the scroll delta as second values.
 * e.g. function(jqEvent, scrollEvent, delta)
 *
 * To stop this, unbind the 'scroll.trackScroll.vertical' or 'scroll.trackScroll.horizontal' event
 * @param {string} direction Scroll direction to track
 * @return {jQuery}
 */
$.fn.trackScroll = function(direction) {
	var curElems = $(this),
		customEventName = 'scroll.trackScroll.' + direction;

	var getVal = function($elem) {
		return direction === 'vertical' ? $elem.scrollTop() : $elem.scrollLeft();
	};

	return curElems.each(function() {
		var $elem = $(this),
			prevVal = getVal($elem);

		$elem.unbind(customEventName).on(customEventName, function(event) {
			var $target = $(event.target),
				newVal = getVal($target),
				delta = newVal - prevVal;
			if (delta) {
				$target.trigger('scroll_' + direction, [event, delta]);
			}
			prevVal = newVal;
		});
	});
};