function preload(images) {
   if (document.images) {
       var i = 0;
       var imageArray = new Array();
       var imageObj = new Array();
       imageArray = images.split(',');
       for(i=0; i<=imageArray.length-1; i++) {
           imageObj[i] = new Image();
          imageObj[i].src=imageArray[i];
       }
   }
}