title: How to keep default scope data even when scope data changes?
body: <p>Keep default $scope data even when scope data changes.</p>
  
  <pre><code>  $scope.data={"a":"hello world"};
  
      $scope.data.a="changed data";
  </code></pre>
  
  <p>now become</p>
  
  <pre><code>$scope.data={"a":"changed data"};
  </code></pre>
  
  <p>how can i get old $scope data.ie, i need - </p>
  
  <pre><code>$scope.data={"a":"hello world"};
  </code></pre>