gistfile1.js

function preload(srcs, callback) {
	var loaded = 0;

	function loadOrError = function() {
		loaded++;
		if (loaded == srcs.length) {
			if (callback) {
				callback();
			}
		}
	}

	for (var i = 0; i < srcs.length; i++) {
		var src = srcs[i];
		var image = new Image();
		image.onload = loadOrError;
		image.onerror = loadOrError;
	}
}

var callback = function () {
  $('#website').fadeIn();
}

var images = ["http://image1.png", "http://image2.png", "http://image3.png", "http://images4.png"];

preload(images, callback);