title: Date days gap should not me more then 20 days
body: <p>I am having fromdate and todate I want if user enters the from date and to date the gap between them should not be ore then 20 days. i.e if user enters from date='30/08/2018' to date='26/09/2018' here the gap is more then 20 days so i want to show a alert using jquery.
  Below is my code</p>
  
  <pre><code> var today = new Date(new Date().getFullYear(), new Date().getMonth(),new Date().getDate());
   $('#startdate').datepicker({
      uiLibrary : 'bootstrap4',
      iconsLibrary : 'fontawesome',
      format : 'dd/mm/yyyy',
      maxDate : function() {
          return $('#enddate').val();
      }
   });
   $('#enddate').datepicker({
      uiLibrary : 'bootstrap4',
      iconsLibrary : 'fontawesome',
      format : 'dd/mm/yyyy',
      minDate : function() {
          return $('#startdate').val();
      }
   });
  </code></pre>