title: Backbone collection: Retrieve distinct values of a collection
body: <p>I have backbone collection of models and would like to retrieve the distinct values of a certain property</p>
  
  <p>If I have loaded data like the following into my collection:</p>
  
  <pre><code>[{brand:'audi',id:'1234'},
  {brand:'audi',id:'3456'},
  {brand:'bmw',id:'3456'}]
  </code></pre>
  
  <p>I would now want to get the distinct brands from the collection. The result should be: </p>
  
  <pre><code>['audi','bmw']
  </code></pre>
  
  <p>Looking at the Backbone and Underscore API I don't see anything obvious to achieve this. 
  My current approach would be to use a library like <a href="http://jslinq.codeplex.com/" rel="nofollow">jslinq</a></p>
  
  <p>Am I missing anything obvious or does somebody have a better suggestion than jslinq?</p>