title: iterate over an object retrieved from _.groupBy
body: <p>With the underscore function groupBy, an array can be grouped by one of its element's properties. The result is an object which has key-value pairs as followed: group > corresponding array fragment.</p>
  
  <pre><code>var words = ['Hey', 'Hii', 'Salut'],
      grouped = _.groupBy(words, 'length');
  </code></pre>
  
  <p>grouped looks like this:</p>
  
  <pre><code>{
    '3': ['Hey', 'Hii'],
    '5': ['Salut']
  }
  </code></pre>
  
  <p>Which would be a simple and secure way to iterate over this, say starting with the highest length followed by the next lowest. This works:</p>
  
  <pre><code>_.each( _.toArray(grouped).reverse(), function(v) {
    console.log(v);
  } );
  </code></pre>
  
  <p>But I think it's not totally correct, because objects are unordered lists, and the right order happens here just by chance.
  Any comments on this?</p>