Get POST method result from PHP code on server in jQuery

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>

<script>
var g_acode = "";
function sendAuthKey()
{
    var fd = new FormData();
    fd.append("name", "Chun Kang");
    jQuery.ajax({
        url: "/ajax.php",
        type: "post",
        data: fd,
        contentType: false,
        processData: false,
        async: false,
        success: function(response)
        {
            alert(response);
        }
    });
}
</script>

<?php

extract( $_POST);

echo "Hey {$name}, howdy?";

?>