Set Session variable using javascript in PHP

Is it possible to set PHP session variables using Javascript?

In JavaScript:

jQuery('#div_session_write').load('session_write.php?session_name=new_value');

In session_write.php file:

<?
session_start();

if (isset($_GET['session_name'])) {$_SESSION['session_name'] = $_GET['session_name'];}
?>

In HTML:

<div id='div_session_write'> </div>

The session is stored server-side so you cannot add values to it from JavaScript. All that you get client-side is the session cookie which contains an id. One possibility would be to send an AJAX request to a server-side script which would set the session variable. Example with jQuery's .post() method:

$.post('/setsessionvariable.php', { name: 'value' });

You should, of course, be cautious about exposing such script.