title: Ascending vs Descending sort order with Async.js sortBy
body: <p>I'm trying to sort an array of objects by their date property using Async.sortBy, from most recent to oldest. A bit of googleing suggests that I reverse sort order by passing obj.date * -1 in the callback instead of obj.date, but this does not have the intended effect. Obviously because the result of that is just NaN.</p>
  
  <p>My dates are in the form 2012-07-12 using today's date as an example.</p>
  
  <p>Sorry fr the brevity and lack of code samples, I'm on the road on my iPad at the moment.</p>
  
  <p>I could just reverse the output array of the sorting I guess but that's not a particularly nice solution.</p>
  
  <pre><code>[{title: "title", date: "2012-07-12"}, {title: "title2", date: "2011-07-12"}]
  </code></pre>