title: jQuery UI Picking a start and end date within range based on start date
body: <p>I'm building a date picker in jQuery ui. What I'm trying to do is set a range, so when they pick the first date the second date appears and gives a 30 day window. I tried this but it doesn't work (it lets the user pick 30 days from today, not 30 from the start date):</p>
  
  <pre><code>var pickDate;
  $( "#datepickerEnd" ).hide();
  $( "#datepickerStart" ).datepicker();
  $( "#datepickerStart" ).change(function(){
      var pickDate = $( "#datepickerStart" ).val();
      $( "#datepickerEnd" ).datepicker({ minDate: pickDate, maxDate: +30 });
      $( "#datepickerEnd" ).show();
  })
  </code></pre>
  
  <p>Another issue I ran into is when I change datepickerStart it'll only set the start range once but not every time I change it. I have to refresh the page to lock in a new start date.</p>