jquery里面的工作会话变量

I am having trouble recording the following _session variable inside my jquery function. I essentially want to grab the value of the coupon code and store it there.

<input type="text" oninput="calculate()" name="couponCode"  id="couponCode"  value="" placeholder="Please Enter Coupon Code" required>
<script>
$(function() {
 $("#signInButton2").click(function(){
<?php $_SESSION['userCoupon'] = echo "<script> $('#couponCode').val(); </script>"; ?> 

});

});

Thanks in advance

Here is a quick and easy using jSON. I will get a lot of flak for using jSON in this manner, but too bad everyone.

This should work just fine...

    $(function()
    {
        $("#signInButton2").click(function()
        {
            var temp = $('#couponCode').val();
            example(temp)
        });
    });


    function example(number)
    {
        $.get("example_set_session.php",
        {
            number: number
        });
    }

in example_set_session.php...

    <?php 

        $example_number = $_GET['number'];

        $_SESSION['userCoupon'] = $example;

    ?>