Javascript object properties visible in console, but undefined?

Question

I'm having trouble figuring out how to access object properties in Javascript. I have a function that returns an object, and I can see that object and all of its properties when it is logged to the console in Safari, but I can't get the property values for other functions. For example trying to alert out one of the properties returns 'undefined'.

The function that generates a object

getProfile : function() {

  FB.api('/me', function(response) {
    facebook.profile.user_id = response.id;
    facebook.profile.name = response.name;
    facebook.profile.firstName = response.first_name;
    facebook.profile.lastName = response.last_name;
    facebook.profile.gender = response.gender;
  });

  FB.api('/me/photos', {limit: 8}, function(response) {
    facebook.profile.numPhotos = response.data.length;
    for (key in response.data) {
      var photoUrl = response.data[key].source;
      eval('facebook.profile.photo' + key + '= photoUrl');
    }
  });

  return facebook.profile;
}

Trying to use that function in another script

function loadProfile() {
  var profile = facebook.getProfile();

console.log(profile);
  alert(profile.name);
}

Answer 1

The function getProfile invokes FB API function FB.api which executes an asynchoronous HTTP request. In your loadProfile function call you call getProfile which immediately returns facebook.profile object which is not populated with data yet since the HTTP request is not finished yet.

Consider following change:

getProfile : function(fCallback) {
  var bInfo = false,
      bPhotos = false;    

  FB.api('/me', function(response) {
    facebook.profile.user_id = response.id;
    facebook.profile.name = response.name;
    facebook.profile.firstName = response.first_name;
    facebook.profile.lastName = response.last_name;
    facebook.profile.gender = response.gender;

    bInfo = true;
    if (bPhotos)
       fCallback(facebook.profile);
  });

  FB.api('/me/photos', {limit: 8}, function(response) {
    facebook.profile.numPhotos = response.data.length;
    for (key in response.data) {
      var photoUrl = response.data[key].source;
      eval('facebook.profile.photo' + key + '= photoUrl');
    }

    bPhotos = true;
    if (bInfo)
       fCallback(facebook.profile);
  });
}

and call this function the following way now:

function loadProfile() {
  facebook.getProfile(function (profile) {
    alert(profile.name);
  });
}

The reason why ou could see fields in the console is because you introspected the object after the asynch call was successfully executed. The alert call however executed immediately in the same thread on a not yet populated object.