q&d js downloadImage & downloadImages

downloadImages.js

window.downloadImage = function(url, cb) {
	var img = new Image();
	img.onerror = function() {
		cb("onerror", img);
	};
	img.onabort = function() {
		cb("onabort", img);
	};
	img.onload = function() {
		cb(false, img);
	};
	img.src = url;
};

window.downloadImages = function(urls, cb) {
	var imgs = new Array(urls.length);
	var c = 0;
	for(var i in urls) {
		(function() {
			var j = i;
			downloadImage(urls[j], function(err, img) {
				if(err) {
					cb(err, imgs);
					cb = function() {};
				} else {
					imgs[j] = img;
					if(++c == urls.length) {
						cb(false, imgs);
					}
				}
			});
		})();
	}
};

gisty