Sharing Data between controllers

'use strict';

angular
  .module('demoApp', [])
  .factory('shareService', shareService)
  .controller('FirstCtrl', FirstCtrl)
  .controller('SecondCtrl', SecondCtrl);
  


  function FirstCtrl ($scope, shareService) {
    
    shareService.store('FirstCtrl', $scope)
    
    $scope.variableOne = 'First Controller Variable';
    $scope.ctrl = 'First Controller';
    
    $scope.getTwo = function() {
      $scope.resTwo = shareService.get('SecondCtrl').variableTwo;
    }
    
  }
  
  
  function SecondCtrl ($scope, shareService) {
    
    shareService.store('SecondCtrl', $scope)
    
    $scope.variableTwo = 'Second Controller Variable';
    $scope.ctrl = 'Second Controller';
    
    $scope.getOne = function() {
      $scope.resOne = shareService.get('FirstCtrl').variableOne;
    }
    
  }
  
  
  function shareService() {
    var memory = {};
    return {
        store: function (key, value) {
            memory[key] = value;
        },
        get: function (key) {
            return memory[key];
        }
    }; 
  }

<!DOCTYPE html>
<html ng-app="demoApp">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.4.x" src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.6/angular.min.js" data-semver="1.4.6"></script>
    <script src="app.js"></script>
  </head>

  <body>
    
    <div ng-controller="FirstCtrl" class="firstCtrl">
      <h4>{{ctrl}}</h4>
      <button ng-click="getTwo()">Get Second Ctrl var</button>
      <p>{{resTwo}}</p>
    </div>
    
    <div ng-controller="SecondCtrl" class="secondCtrl">
      <h4>{{ctrl}}</h4>
      <button ng-click="getOne()">Get First Ctrl var</button>
      <p>{{resOne}}</p>
    </div>
    
  </body>

</html>

/* Put your css in here */

.firstCtrl {
  display: block;
  background: #f5f4f3;
  border-radius: 4px;
  padding: 10px;
  border: 1px solid #eee;
  margin-bottom: 20px;
}

.secondCtrl {
  display: block;
  background: #f5f4f3;
  border-radius: 4px;
  padding: 10px;
  border: 1px solid #eee;
  margin-top: 20px;
}