title: Identify object in angular js has changed
body: <p>I have a backend object that i receive from the server and sent to server.
  I give a permission to my users to change the backend object.
  I would like to identify if the backend object has changed from the save point.</p>
  
  <p>How can i identify it?</p>
  
  <p>For example:
  I have a module called </p>
  
  <pre><code>app.controller('PanelCtrl', function($scope, $http) {
  $scope.action = "";
  $scope.selectedItem = "";
      $scope.compoundItem = [];
  
  ...
  </code></pre>
  
  <p>I have in the compound item array of Objects.
  I would like to know if something is changed whether the change occures in the primitives and whether in the compoundItem...</p>