如何在javascript函数中使用php里面的javascript变量

I'm using JavaScript to redirect a page with dynamic parameter.

Here is the code, I had to use the PHP function inside JavaScript. It works but it isn't using the javascipt variable

<script type="text/javascript">
var $map = jQuery.noConflict();
       $map(document).ready(function(){
            $map("#map_search").click(function(){
                  var staffname = $map("#staffname").val();//alert(staffname);

                  var from = $map("#cdate_from").val();
                  var to = "<?php echo site_Encryption(from); ?>";alert(to);
                  var status = $map("#status").val();
                  window.location = "http://localhost/staff/booking.php?date="+to+"&tdate="+to;


var to = "<?php echo site_Encryption(from); ?>";alert(to);

Here I use the PHP function and "from" is JavaScript variable that I want to use.

You can do an ajax request, something like:

var from = blablah...;
$.getJSON("encryption.php", {from : from}, function (data)
{
alert(data.to);
});

encryption.php :

<?php
blabla...
echo json_encode(array("to" => site_Encryption($_GET["from"])));
?>

(It's a sample code, don't copy-paste, read some ajax tutorials ^^)

An alternative could be to make the encryption on client side.