Animate scroll top within FB iFrame

scroll_top.js

function scroll_to_top() {
    FB.Canvas.getPageInfo(function (pageInfo) { 
      var iframe_scroll_y = pageInfo.scrollTop;
      var target_div_y = $('#dr_dre').position().top;
      if (iframe_scroll_y > target_div_y) {
          var animOptions = {

              step: function () {
                FB.Canvas.scrollTo(0, this.y);
              },
                duration: 200
            };
            $({ y: iframe_scroll_y }).animate({ y: target_div_y }, animOptions);
        }
    });
}