title: jQuery datepicker - How to populate due date from chosen date
body: <p>I am a rails newbie trying to use Datepicker to set up reservations in a rental app. I have it working for the start at date and would like to set a due at for 2 days later. I've gotten stuck and am hoping for some advice on how to proceed...</p>
  
  <p>jQuery</p>
  
  <pre><code>$('#rental_start_at').datepicker
      dateFormat: 'yy-mm-dd',
      onSelect: (dateText) 
  </code></pre>