jQuery $.ajax(), pass success data into separate function

Works fine for me:

<script src="https://stackoverflow.com/jquery.js"></script>
<script>
var callback = function(data, textStatus, xhr)
{
    alert(data + "\t" + textStatus);
}

var test = function(str, cb) {
    var data="Input values";
    $.ajax({
        type: 'post',
        url: 'http://www.mydomain.com/ajaxscript',
        data: data,
        success: cb
    });
}
test('Hello, world', callback);
</script>