index.htm
<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<title>123</title>
<style>
body{color:#000;background-color:#fff;font-family:Georgia,'Bookman Old Style',Verdana;font-size:14px;}
.current{color:Crimson;font-weight:bold;}
.other{color:#000;font-weight:normal;}
.or{color:Darkorange;}
li{cursor:pointer;}
</style>
<script src="http://code.jquery.com/jquery-latest.min.js"></script>
<script>
$(document).ready(function(){
var lis=$('#lang li');
lis.each(function(index){
$(this).click(function(){
$('#resp').html('Wait...');
lis.attr('class','other');
$(this).attr('class','current');
$.get('sess.php',{current:index},function(data){$('#resp').html(data);})
});
});
});
</script>
</head>
<body>
<ul id="lang" class="tabs">
<li>Русский</li>
<li>English</li>
</ul>
<div id="resp"></div>
</body>
</html>
sess.php
<?php
session_start();
$_SESSION['current']=$_GET['current'];
echo 'Индекс элемента, имеющего класс <b>current</b>, равен <b class="or">'.$_SESSION['current'].'</b>';
?>