title: How to sum up all items in an object array?
body: <p>I have an array of objects:</p>
  
  <pre><code>var test = [{"a":1, "b":2, "c":3}, {"a":4, "b":5, "c":6},{"a":7, "b":8, "c":9}];
  </code></pre>
  
  <p>I would like to add up all the values in object b to get the total 15</p>