Simple image preloader

preload.js

/**
    Simple image preloading
    Dave Taylor http://the-taylors.org

    Usage:
    var images = ['img.png', 'img2.png'];
    window.imagePreload(images, function(errorUrls){
        this == images;
    });

    @license The MIT License (MIT)
    @preserve Copyright (c) <2011> <Dave Taylor http://the-taylors.org>
*/
/*jslint browser: true, vars: true, white: true, forin: true, indent: 4 */
/*global define*/
(function(){
    'use strict';

    var imagePreload = function(imageUrls, callback){

        var ln = imageUrls.length, i,
            images          = [],
            errors          = [],
            imagesLoaded    = [],
            loaded          = 0,
            timeout         = 1000,
            img;

        function imageLoaded() {
            if (this && this.imagePreloadTimeout) {
                clearTimeout(this.imagePreloadTimeout);
            }
            loaded+=1;
            if (loaded === ln) {
                callback.call(imageUrls, errors);
            }
        }
        function imageError() {
            errors.push(this);
            imageLoaded.call(this);
        }
        function imageTimeout(img) {
            imageError.call(this);
        }
        function addTimeout(img, timeout){
            img.imagePreloadTimeout = setTimeout(function(){
                imageTimeout.call(img);
            }, timeout);
        }

        for (i = 0; i < ln; i+=1) {
            img = new Image();
            img.src = imageUrls[i];
            if (img.complete) {
                imageLoaded.call(this);
            } else {
                img.onload = imageLoaded;
                img.onerror = imageError;
                img.onabort = imageError;
                addTimeout(img, timeout);
            }
            images.push(img);
        }

    };

    if (window.define && window.define.amd) {
        define(function(){
            return imagePreload;
        });
    } else {
        window.imagePreload = imagePreload;
    }

}());