From JavaScript in PHP (method GET)

From JavaScript in PHP (method GET)

<script type="text/javascript">

var userName2 = 'Переменная';

</script>

<?php
if (isset($_GET['u_name']))
{
    echo "Значение JavaScript-переменной: ". $_GET['u_name'];
}

else
{
    echo '<script type="text/javascript">';
    echo 'document.location.href="' . $_SERVER['REQUEST_URI'] . '?u_name=" + userName2';
    echo '</script>';
    exit();
}
?>