Parallax scrolling

gistfile1.txt

// scroll

	var parallaxEmts = $("[data-parallax]");
	for (var x=0,max=parallaxEmts.length;x<max;x++) {
		var emt = $(parallaxEmts[x]);
		emt.data("page-y", emt.offset().top);
	};

	function parallax() {
		if (documentIsHidden()) return;

		var yPos = window.pageYOffset;
		var ww = $(window).width();

		for (var x=0,max=parallaxEmts.length;x<max;x++) {
			var emt 			= $(parallaxEmts[x]),
				windowHeight 	= $(window).height(),
				emtTop 			= emt.data("page-y");

			if (emtTop == null) {
				emtTop = emt.offset().top;
				emt.data("page-y", emtTop);
			}

			var dist 			= (windowHeight / 2) - (emtTop - yPos),
				speed 			= (emt.data("parallax") == "slow") ? 0.05 : 0.1;

			// disable for mobile

			if ( ww <= 992 ) {
				dist = 0;
				emt.removeData("page-y");
			}

			emt.css({"transform": "translateY(" + (-dist * speed) + "px)"})
		}
	}
	$(window).scroll(parallax);
	$(window).resize(parallax);
	parallax();