How to get "scrollTop"-value of FB.Canvas.getPageInfo

Question

So far I can alert the "scrollTop"-value of "FB.Canvas.getPageInfo":

FB.Canvas.getPageInfo(
      function(info) {
          alert('scrollTop: ' + info.scrollTop);
      }
  );

Now I would like to use this value in one of my functions, but I don't know how. The following is not working:

function test() {
    var fbScrollTop = FB.Canvas.getPageInfo();
    alert(fbScrollTop);
}

How can I access the the value?

Rodrigo · Answer 1 · 2013-05-20T14:09:07.080

I don't know if it's useful yet. But now I can center my divs in my facebook app. Here is the function:

jQuery.fn.center = function () {
    var temp = this;
    FB.Canvas.getPageInfo(
    function(info) {
            $(temp).css("position","absolute");
            $(temp).css("top", Math.max(0, ((info.clientHeight - $(temp).outerHeight()) / 2) + info.scrollTop) + "px");
            $(temp).css("left", Math.max(0, ((info.clientWidth - $(temp).outerWidth()) / 2) + info.scrollLeft) + "px");
        }
    );

    return this;
}

And I use like that:

var loading = $("#loading");
    loading.center();

Alexander Nenkov · Answer 2 · 2012-12-19T13:01:41.773

0

Just combine both

function test() {
    var fbScrollTop;
    FB.Canvas.getPageInfo(function(info) {
        fbScrollTop = info.scrollTop;
        alert(fbScrollTop);
    });
}

edited Dec 19 '12 at 13:01

answered Dec 19 '12 at 11:12

Alexander Nenkov

2,910
20
28

This alerts `undefined`. Any other idea? – chris Dec 19 '12 at 12:14
Fixed. For unknown (to me) reason, everything you do with the info object should be inside the getPageInfo function. – Alexander Nenkov Dec 19 '12 at 13:02
Thanks, that works perfectly! Is it also possible to access the variable `fbScrollTop` outside of the function `test()`? Something like `test(); console.log(fbScrollTop)` – chris Dec 19 '12 at 13:22
actually I couldn't find a way to use it outside of getPageInfo – Alexander Nenkov Dec 19 '12 at 14:27
same here and that is exactly what I need :-( But thanks for your help! – chris Dec 19 '12 at 19:01

score 0 · Answer 3 · answered Dec 19 '12 at 19:34

0

Most of the methods available in the SDK are asynchronous - this means that the response will not be available until the provided callback is invoked (with the response).

answered Dec 19 '12 at 19:34

Sean Kinsey

37,689
7
52
71

How to get "scrollTop"-value of FB.Canvas.getPageInfo

3 Answers3