charCodeAt() : get Unicode of the character at index in JavaScript

JS Script :

<html>
<body>
<script type="text/javascript">
var str="c4learn.com/javascript";
document.write("Unicode of First character : " + str.charCodeAt(0) + "<br />");
document.write("Unicode of Last character  : " + str.charCodeAt(str.length-1));
</script>
</body>
</html>

Output in browser :

Unicode of First character : 99
Unicode of Last character : 116