$.ajax({
    type: "POST",
    url: "panel.aspx",
    data: username + ";" + pw,
    success: function (result) {
        $("#midiv").html(result);

    }
});

$.ajax({
    type: 'POST',
    url: 'panel.aspx',
    data: {
          'username=' + uname "&password=" + pword,
//Note:- uname and pword are variables and not text
          },
    success: function (result) {
        $("#midiv").html(result);

    }
});

Dim uname, pword
uname = Request.Form("username")
pword = Request.Form("password")

$.ajax({
    type: "POST",
    url: "panel.aspx",
    data: {
        username: "foo",
        pw: "bar"
    },
    success: function (result) {
        $("#midiv").html(result);
    }
});

$.ajax({
    type: "POST",
    url: "panel.aspx",
    data: 'username=' + username + "&password=" + pw,
    success: function (result) {
        $("#midiv").html(result);

    }
});

$.ajax({
    type: "POST",
    url: "panel.aspx",
    data: {username: username, password: pw}
}).done(function(result) {
    $("#midiv").html(result);
});

$user = $_POST['username'];
$pw = $_POST['password'];