如何从循环中收集Facebook API请求的响应？

Question

我试图收集在循环中调用的FB API异步请求的结果。我用下一个代码：

    function getPicturesByUserIds(friendsIdList) {
        var userPictures = [];
        for (var i = 0; i < friendsIdList.length; i++) {
            (function () {
                var userId = friendsIdList[i];
                var j = i;
                var friendsIdListLength = friendsIdList.length - 1;
                FB.api('/'+userId+'/picture?type=large', function (responce) {
                    if (responce && !responce.error) {
                        userPictures[userId] = responce.data.url;
                    }
                    if (j >= friendsIdListLength) {
                        console.log(userPictures);
                        sendPicturesAndGetResponse(userPictures);
                    }
                });
            })();
        }
    }

此代码适用于Chrome，但在Firefox数组中，userPictures为空。