Sending multiple variables to PHP

I have the following jQuery-enhanced Javascript within a HTML page:

<script>
     $(document).ready(function(){           
        $("#sb").click(function(e){
            e.preventDefault();
            getusername = "Yes";
            getpassword = "Yes";
            getusername = encodeURIComponent(getusername);//url encodes data
            getpassword = encodeURIComponent(getpassword);//url encodes data
            $.ajax({
               type: "POST",
               url: "get_login.php",
               data: {'username': getusername, 'password':getpassword},
               dataType: "json",
               success: function(data) {
                  $("#mes开发者_开发技巧sage_ajax").html("<div class='successMessage'>" + data.message +"</div>");
           }
            });
        });
    });
</script>

My php is as follows:

if(isset($_POST['username']) && isset($_POST['password'])){
    echo json_encode(array('message' => 'Tester'));
}

The script isn't working however. I think it is to do with the way I am posting data from the browser. Perhaps I am incorrectly setting username and password and it is failing upon the isset statement?

Currently, the page does nothing. The button click event handler is triggering...but the message_ajax div in my HTML page isn't updating with correct response...

---

change the line

  $("#message_ajax").html("<div class='successMessage'>" + data.message +"</div>");

to

  $("#message_ajax").html("<div class='successMessage'>" + data.message +"</div>");

and try !!!

---

you need to change the mime header... your ajax is expecting json as a respons so you need to set the correct header.

header('Content-type: application/json');

http://docs.jquery.com/Specifying_the_Data_Type_for_AJAX_Requests