Dilettante_Pro,
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>jQuery UI</title>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script src="//ajax.aspnetcdn.com/ajax/jquery.ui/1.10.3/jquery-ui.min.js"></script>
<link rel="stylesheet" href="https://ajax.aspnetcdn.com/ajax/jquery.ui/1.10.3/themes/sunny/jquery-ui.css">
<style type="text/css">
input {width: 200px; text-align: left}
</style>
<script type="text/javascript">
$(function() {
$('#datep').datepicker({onSelect : function() {
var currentDate = $( this ).datepicker( "getDate" );
alert(currentDate/1000|0);
}});
/* $('#datep').on('change', function() {
var ms = new Date($(this).val());
alert(ms.valueOf());
});*/
});
</script>
</head>
<body>
<form>
<div class="ui-widget">
<label for="datep">Дата: </label><input id="datep"/>
</div>
</form>
</body>
</html>