lazy load javascript idea

lazyLoad

var A = AUI();


var lazyLoadObj = A.all('.lazy-load');
var winHeight = window.innerHeight;
var getCumulativeOffset = function (obj) {
	var top = 0;

	if (obj.offsetParent) {
		do {
			top  += obj.offsetTop;
		} while (obj = obj.offsetParent);
	}
	return {
		y : top
	};
};
var lazyLoad = function (arg) { 
	var scrollY = window.scrollY;

	lazyLoadObj.each(
		function (e) {
			var posY = getCumulativeOffset(this._node).y;
			var loadPos = posY - winHeight;
			var src = this.getAttribute('src');
			var datasrc = this.getAttribute('datasrc');

			if (arg == "winHeight") {
				argument = winHeight;
				loadPos = posY;
			}
			if (arg == "scrollY") {
				argument = scrollY;
			}

			if (argument > loadPos) {
				if (src != datasrc) {
					this.setAttribute('src', datasrc);
				}
				if (!this.hasClass('lazy-loaded')) {
					this.addClass('lazy-loaded');
				}
			}
		}
	);
};

if (lazyLoadObj.get('length').length > 0) {
	lazyLoad ("winHeight"),

	A.on(
		'scroll', 
		function () {
			lazyLoad ("scrollY");
		}
	);
}