// clear form values
function clearDefault(el) {
    if (el.defaultValue==el.value) el.value = ""
}

// swap images
function swapImages(imageID, imageUrl) {
   var largeImage = window.document.getElementById( imageID );
   largeImage.src = imageUrl;
}

// Email Truck Url
function EmailTruck(subject)
{
   document.location = "mailto:?subject=Check Out This Truck!&body="+location.href;
}

// check all checkboxes
function CheckAllItems(item_count, item_name)
{
   for (i=0; i < item_count; ++i)
   {
      eval("document.getElementById('" + item_name + i + "').checked = true");
   }
}

// uncheck all checkboxes
function UncheckAllItems(item_count, item_name)
{
   for (i=0; i < item_count; ++i)
   {
      eval("document.getElementById('" + item_name + i + "').checked = false");
   }
}

// toplevel method to support above methods
function ItemSelection(item_count, item_name)
{
   if (document.getElementById('checkallbox').checked)
   {
      CheckAllItems(item_count, item_name);
   }
   else
   {
      UncheckAllItems(item_count, item_name);
   }
}