/**
  * imageURLs   Array() of image URLs with indexes from 0 to n
  */
 function preloadImages (imageURLs) {
  if (typeof imageURLs != "undefined" && imageURLs.length > 0) {
   var images = new Array();
   for (var i = 0; i < imageURLs.length; i++) {
    images[i] = new Image();
    //images[i].onload = function () { alert('loaded') }
    images[i].src = imageURLs[i];
   }
  }
 }