title: Javascript: calculate number of days in month for a given year
body: <p>I have a HTML page with 3 dropdowns for the month, day and year and I was wondering if there was a way to populate the month drop down properly depending on the month and year.</p>
  
  <p>I haven't done this before on the client side, but it looks like a lot of controls like the jQuery DatePicker are doing that behind the scenes.</p>