How To Count Capital And Small Letters Using JavaScript

<script language="javascript" type="text/javascript">
function check_odd_even() 
{
var str = prompt("Enter your word to count the Capital and Small Letters.");
	 var count=0,small=0;
	 var len=str.length;
 for(var i=0;i<len;i++) {
if(/[A-Z]/.test(str.charAt(i))) 
	{
	count++;
}
	else {
	 small++;
	 }
}
document.write("<h3 style='text-align:center;'><b style='color:blue;'>Orignal word :</b> <b style='color:red;'>" + str + "</b> <br> No. of Capital Letters is <b style='color:blue;'>" +count + "</b>. </h3>");
document.write("<h3 style='text-align:center;'><b style='color:blue;'>Orignal word :</b> <b style='color:red;'>" + str + "</b> <br> No. of Small Letters is <b style='color:blue;'>" +small + "</b>. </h3>");
return count;
}
</script>