jQuery Image Preloader script + Refactor a bit + Code Cleanup + Add support for non-ES5 browsers

jquery.imageloader.js

/*!
* imageloader : a jquery plugin for preloading images
* Version: 0.2.0
* Original Author: Nick Jonas - @nick-jonas
* Edited by: Ernesto Méndez - @derdesign
* Website: http://www.workofjonas.com
* Gist: https://gist.github.com/derdesign/5588986
* Gitbub: https://github.com/modernassembly/imageloader
* License: MIT
*/
 
;(function ($) {
 
  $.imageloader = function(userOptions) {
 
    var loadCount = 0;
    var completedUrls = [];
    
    var options = $.extend({
      urls: [],
      onComplete: function() {},
      onUpdate: function(ratio, image) {},
      onError: function(err) {}
    }, userOptions);
        
    for (var i=0,urls=options.urls,len=urls.length; i < len; i++) {
      (function(item) {
        var img = new Image(), error = false;
        img.src = item;
        img.onerror = function() {
          loadCount++;
          options.onError('Error loading image: ' + item);
        };
        $('<img/>').attr('src', item).load(function(res) {
          loadCount++;
          options.onUpdate(loadCount/len, urls[loadCount-1]);
          if (loadCount === len) options.onComplete();
        });
      })(urls[i]);
    }
 
  };
 
})(jQuery);