maps.js

var MapApp = angular.module('GoogleMapsInitializer', []);
MapApp.factory('Initializer', function($window, $q){
    //Google's url for async maps initialization accepting callback function
    var asyncUrl = 'https://maps.googleapis.com/maps/api/js?key=AIzaSyCOt9IYHpYN22m7alw_HKi5y5WBgu57p4s&v=3.exp&sensor=true&callback=googleMapsInitialized',
        mapsDefer = $q.defer();

    function init () {
            var gMapsLoader = $.getScript(asyncUrl);
            
            gMapsLoader.fail(function (err) {
              return mapsDefer.reject(err);
            });

        //Callback function - resolving promise after maps successfully loaded
        $window.googleMapsInitialized = mapsDefer.resolve;

    }

    init();

    //Usage: Initializer.mapsInitialized.then(callback)
    return {
        mapsInitialized : mapsDefer.promise,
        reload: init
    };
});
MapApp.directive("cityState", ['Initializer', function (Initializer) {
  return {
    template: '<em>{{locationData.formatted_address}}</em>',
    scope: {
      locationData: "=cityState"
    },
    link: function (scope) {
      Initializer.mapsInitialized
      .then(function () {

      });
    }
  };
}]);