function preload_images()
{
  var d = document;
  if (!d.preloaded_images) d.preloaded_images = new Array();

  var i, j = d.preloaded_images.length, a = preload_images.arguments;
  for(i = 0; i < a.length; i++)
  {
    if (a[i].indexOf("#") != 0)
    {
      d.preloaded_images[j] = new Image;
      d.preloaded_images[j++].src = a[i];
    }
  }
}

function shopping_cart_plus()
{
  document.getElementById('quantity').value++;
}

function shopping_cart_minus()
{
  var quantity = document.getElementById('quantity');
  if (quantity.value > 1) quantity.value--;
}