jQuery validation File extension

jQuery validation

HTML

<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.10.0/jquery.validate.min.js"></script>
<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/css/bootstrap-combined.min.css">
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.14/themes/base/jquery-ui.css">
<script src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.11.0/additional-methods.js"></script>

JavaScript

var fileName, fileExtension;
fileName = "file.jpeg";
fileExtension = fileName.substr((fileName.lastIndexOf('.') + 1));
console.log (fileExtension);