check vowel or constant
<!doctype html>
<html>
<body>
<script>
var ch='c';
if(ch=='a' || ch=='e' || ch=='i' || ch=='o' || ch=='u')
document.write("<b>"+ch+"</b>" + " is a Vowel");
else if(ch=='A' || ch=='E' || ch=='I' || ch=='O' || ch=='U')
document.write("<b>"+ch+"</b>" + " is a Vowel");
else
document.write("<b>"+ch+"</b>" + " is a Consonant");
</script>
</body>
</html>