Confusion about Javascript 'then' behaviour

Question

I have the following code in an Angular controller...

function doWork() {
  // show the loading modal
  $scope.modal = $ionicLoading.show({
    content: 'Fetching current location...',
    showBackdrop: false
  });

  console.log("get orig pos");

  // get the position
  PositionService.getPosition(posOptions)
    .then(function(positionArr) {
      // got 1st location // this doesn't execute!
      console.log("got original pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
      $scope.modal.hide();
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
      $timeout(function() {
        $scope.modal.hide();
      }, 3000);          
    });

    console.log("get next pos");

  PositionService.getPosition(posOptions)
    .then(function(positionArr) {
      // got 2nd location // this does execute!
      console.log("got new pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
    });
 }

When I run the program the PositionService.getPosition function is invoked twice, as I would expect, but only one of the then parts is executed. Shouldn't both of the then blocks be executed or am I misunderstanding how this works in Javascript? This is the content of the getPosition function...

   getPosition : function(posOptions) {
      return $cordovaGeolocation
        .getCurrentPosition(posOptions)
        .then(function(position) {
          positionArr = positionArr.concat({
            position: position,
            status: 'new'
          });
          return positionArr;
        }, function(err) {
          console.log("PositionService: error getting position");
          return err;
        });
    },

EDIT:

Here is the console output as requested...

Answer 1

You should be chaining your calls to the position service:

var p1 =  PositionService.getPosition(posOptions)
    .then(function(positionArr) {
      // got 1st location
      console.log("got original pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
      $scope.modal.hide();
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
      $timeout(function() {
        $scope.modal.hide();
      }, 3000);          
    });

var p2 = p1.then (function() {
     return PositionService.getPosition(posOptions);
   }).then(function(positionArr) {
      // got 2nd location
      console.log("got new pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
    });

Answer 2

First .then() callback is a 'success' and the other is 'error'. So it's one of those two. Ex. http request can be either '200' or '404' (or other error).

See: http://blog.mediumequalsmessage.com/promise-deferred-objects-in-javascript-pt1-theory-and-semantics