title: How to sum value of two json object key?
body: <pre><code>&quot;bills&quot;: [
      {
          &quot;refNo&quot;: 17,
          &quot;billDate&quot;: &quot;1-apr-2016&quot;,
          &quot;dueDate&quot;: &quot;30-apr-2016&quot;,
          &quot;pendingAmount&quot;: 4500,
          &quot;overdueDays&quot;: 28
      },
      {
          &quot;refNo&quot;: 20,
          &quot;billDate&quot;: &quot;15-apr-2016&quot;,
          &quot;dueDate&quot;: &quot;3-may-2016&quot;,
          &quot;pendingAmount&quot;: 56550,
          &quot;overdueDays&quot;: 15
      }
  ]
  </code></pre>
  <p>I want to sum &quot;pendingAmount&quot; field.
  It should be return like pendingAmount: 61050</p>