title: Object.length undefined in javascript
body: <p>I have an javascript object of arrays like,</p>
  
  <pre><code>var coordinates = {
       "a": [
           [1, 2],
           [8, 9],
           [3, 5],
           [6, 1]
       ],
  
           "b": [
           [5, 8],
           [2, 4],
           [6, 8],
           [1, 9]
       ]
   };
  </code></pre>
  
  <p>but <code>coordinates.length</code> returns undefined.
  <a href="http://jsfiddle.net/mpsbhat/3wzb7jen/" rel="noreferrer">Fiddle is here</a>.</p>