Javascript Reference: Dropdown - Move item up/down a dropdown

 
<input type="button" onclick="shift('items', 'up')" value="Up" />
<input type="button" onclick="shift('items', 'down')" value="Down"/>
 

 
function shift(id, direction)
{
	var items = document.getElementById(id);
	var oldIndex = items.selectedIndex;
 
	if (oldIndex != -1)
	{	
		with (items)
		{
			if (direction == 'up')
				var newIndex = (oldIndex == 0) ? options.length - 1 : oldIndex - 1;
			else if (direction == 'down')
				var newIndex = (oldIndex == options.length - 1) ? 0 : oldIndex + 1;
			else
				return false;
 
			var a = new Option(options[oldIndex].text, options[oldIndex].value);
			var b = new Option(options[newIndex].text, options[newIndex].value);
			options[oldIndex] = b;
			options[newIndex] = a;					
			selectedIndex = newIndex;
		}
	}
}