title: updating Json object
body: <p>I have a json object that I need to update. The original object is a list that looks like this:</p>
  
  <pre><code>[
    {
      "firstName":"Jane",
      "lastName":"Smith"
    },
    {
      "firstName":"Jack",
      "lastName":"Brown"
    }
  ]
  </code></pre>
  
  <p>For each element in the list, we have an extra field, "age", that needs to be added at run-time, so the result should look like the following:</p>
  
  <pre><code>[
    {
      "firstName":"Jane",
      "lastName":"Smith",
      "age": "21"
    },
    {
      "firstName":"Jack",
      "lastName":"Brown",
      "age": "34"
    }
  ]
  </code></pre>
  
  <p>Any suggestions how to do this so the result is still json?</p>
  
  <p>Thanks.</p>