How to scroll in a facebook app

fb-scroll.js

function _scrollToTop () 
{
    FB.Canvas.getPageInfo(
        function(pageInfo) 
        {
            $({ y: pageInfo.scrollTop }).animate(
                { y: 0 }, 
                {
                    duration: 1000,
                    step: function(offset) 
                    {
                        FB.Canvas.scrollTo(0, offset);
                    }
                }
            );
        }
    );
}