title: Date show NaN-aN-aN
body: <p><a href="https://i.stack.imgur.com/ulmmz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ulmmz.png" alt="" /></a></p>
  <p>when I am not selected start date and end date then it shows me NaN-aN-aN. I need to show null in request parameter. I use ajax for request and use flagpicker package for calendar</p>