How can i add php content or php variable inside Java-script alert box?!
I tried to make it work few ways but it is only popping up a blank box rather than the contents of php variable.

Here is the code:

<script language=javascript>

    $(document).ready(function() {

        $(#a).blur(function() {           

            <?php $b = $_POST['a'];



            if(isset($_POST['update'])) {

            mysql_query(UPDATE tbl_travel set fld_a='.$_POST[$b].' where fld_id = '.$_POST[id].' ) or die(mysql_error());

            } ?>



                alert (<?php $b ?>);

           });

    });

</script> 

Thank You for your Help :)