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(function() {
  'use strict';
 
  angular
    .module('testApp')
    .service('testService', testService)
    .controller('testCtrl', testCtrl)
    .controller('testCtrl2', testCtrl2);
 
  function testService($http, $q) {
 
    // will hold backend posts
    var posts = undefined;
 
    // fetch all posts in deferred technique
    this.getPosts = function() {
 
      // if posts object is not defined then start the new process for fetch it
      if (!posts) {
 
        // create deferred object using $q
        var deferred = $q.defer();
 
        // get posts form backend
        $http.get('https://jsonplaceholder.typicode.com/posts')
          .then(function(result) {
            // save fetched posts to the local variable
            posts = result.data;
            // resolve the deferred
            deferred.resolve(posts);
          }, function(error) {
            posts = error;
            deferred.reject(error);
          });
 
        // set the posts object to be a promise until result comeback
        posts = deferred.promise;
      }
 
      // in any way wrap the posts object with $q.when which means:
      // local posts object could be:
      // a promise
      // a real posts data
      // both cases will be handled as promise because $q.when on real data will resolve it immediately
      return $q.when(posts);
    };
 
  }
 
  function testCtrl($scope, testService) {
    $scope.getPosts = function() {
      testService.getPosts()
        .then(function(posts) {
 
          console.log(posts);
 
        });
    };
 
    $scope.getPosts();
  }
 
  function testCtrl2($scope, testService) {
    $scope.getPosts = function() {
      testService.getPosts()
        .then(function(posts) {
 
          console.log(posts);
 
        });
    };
 
    $scope.getPosts();
  }
 
})();