[Natch]

Yeah - give it a value in your SELECT and test for that value in the javascript before throwing to the alter...

Try this

<script type="text/javascript">
<!--
function gimmesomesugar(sugar)
{
	var somesugar = sugar.split(":");
	if(somesugar.length==1) 
		{ return false; }
	alert( somesugar[0], somesugar[1] );
}
//-->
</script>