var currentindex = 0;

img= new Image(); 
function changeImage() {
  if (currentindex==imgArray.length)
    currentindex = 0;
  var img_name = imgArray[currentindex++];
  img.src="images/"+img_name;
  document.images['product_img'].src = 'images/ajax-loader.gif';
  document.images['product_img'].style.visibility = 'visible';
  document.images['arrow_img'].style.visibility = (imgArray.length>1?'visible':'hidden');
  document.getElementById('prodcode').innerHTML = '<b>product code:</b> '+img_name.replace('.jpg','');
  document.getElementById('imginfo').innerHTML = '<b>'+currentindex+'</b> of <b>'+imgArray.length+'</b><br><a href="_'+img_name.replace('.jpg','.php').replace(/ /g,'')+'"><b>view</b></a>';
  showImage();
}
function showImage() {
  if (img.complete) {
    document.images['product_img'].src = img.src;
  } else {
    setTimeout("showImage()", 1500);
  }
}