How to insert javascript value into the php session variable

I want to insert javascript value into the php session variable but inside the javascript function.

Here is what I have tried and it is not working:

function languageChange()
{
 var lang = $('#websites1 option:selected').val();
 <?php $_SESSION['SESS_LANGUAGE']?> = lang;
 alert(<?php echo $_SESSION['SESS_LANGUAGE']?>);
}

Solution

You cannot access it directly (the way you are doing). However, it can be done using AJAX. Here is the perfectly working solution.

Here is the HTML:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>1</title>
</head>

<body>
<form id="form1" name="form1" method="post" action="">
    <label for="websites1">Websites</label>
    <select name="websites1" id="websites1">
        <option value="Design">Design</option>
        <option value="Dev">Dev</option>
        <option value="Ecom">Ecom</option>
    </select>
</form>
<script type="text/javascript" src="js/jquery_1.7.1_min.js"></script> 
<script type="text/javascript">

$(document).ready(function() {

    function languageChange()
    {
         var lang = $('#websites1 option:selected').val();

        return lang;
    }


    $('#websites1').change(function(e) {                    

        var lang = languageChange();

        var dataString = 'lang=' + lang;

        $.ajax({

            type: "POST",
            url: "pass_value.php",
            data: dataString,
            dataType: 'json',
            cache: false,
            success: function(response) {

                    alert(response.message);

                }
        });

        return false;

    });

});

</script>
</body>
</html>

Here is the AJAX part:

//pass_value.php

<?php session_start();

$_SESSION['SESS_LANGUAGE'] = $_POST['lang'];

$_SESSION['SESS_LANGUAGE'] = 'This is my PHP session var --->'.$_SESSION['SESS_LANGUAGE'];

print json_encode(array('message' => $_SESSION['SESS_LANGUAGE']));
die();


?>

EDIT 1:

Once you run the code, simply select any of the other options from the dropdown menu and you will receive an alert that gives you the value of the php session variable along with the custom text that I added to it.

EDIT 2:

If you want to run my solution on your end, make sure you point to core jQuery js file correctly. My jquery code points to src="js/jquery_1.7.1_min.js". Make sure you update this.