I have this function, which is doing an asynchronous call to FB.api method. Now, i am looping over some data and capturing result of the above method call successfully.
However, I am using a .each loop and I really can not figure out how to place my callback in this method, so that the outer method is only executed once.

Here are the functions I am using:

ask_for_perms($(this).val(),function(result) {
  $('#some-div').html('<a onclick = "get_perms(result);" >get perms</a>');
});
function ask_for_perms(perms_requested,cb) {
    var request = [];
    $.each(perms_requested,function(i,permission) {
        FB.api({
            method: 'users.hasAppPermission',
            ext_perm: permission
            }, function(response) {
            if (response == 0) request.push(permission);
            request.join(',');
            cb(request); // cb is called many times here.
        });
    });
}

I am trying to return the request string from ask_for_perms function. Can anyone suggest me on where to place a proper callback to ask_for_perms. Right now, however, it works for me, but the callback is being called many times since it is inside a for loop.

referencing: returning a variable from the callback of a function