jQuery addClass example
Change class name on click in jQuery
HTML
<script src="//cdn.jsdelivr.net/parsleyjs/2.4.3/parsley.min.js"></script>
<form role="form">
<div class="form-group">
<label for="name">Name:</label>
<input type="text" class="form-control" id="name" name="name" pattern="^([a-zA-Z\s]{3,})$" required>
</div>
<div class="form-group">
<label for="email">Email address:</label>
<input type="email" class="form-control" id="email" name="email" required>
</div>
<button type="submit" class="btn btn-default">Subscribe</button>
</form>
JavaScript
var $form = $("form");
$form.parsley().on("form:submit", function(){
return false; // avoid submitting
});