source: http://docs.buddyforms.com/article/401-ajax

ajax.php

<?php
Form::open ("test", $values, ["ajax" => "finishCallback"]);
Form::hidden ("id");
From::Button ("Submit");
Form::close ();
?>
<script>
function finishCallback (data) {
    console.log (data.status);
    console.log (data.message);
}
</script>    

<?php
    // Reply example
    $reply = ["status" => "OK", "message" => "all is good"];
    header ("Content-type: application/json");
    echo json_encode ($reply);