JSFiddle - React, Tailwind, and code Playground

HTML

<div data-only="5" class="datepicker">foo</div>

JavaScript

(function() {
  var DateDisabler;

  DateDisabler = (function() {

    function DateDisabler(only) {
      this.only = only;
    }

    DateDisabler.prototype.beforeShowDay = function(date) {
      console.log(this.only);
      if (parseInt(this.only) === date.getDate()) {
        return [true, 'available', 'This date is a good date'];
      } else {
        return [false, 'unavailable', 'This date is NOT good'];
      }
    };

    return DateDisabler;

  })();

  jQuery(function() {
    return $('.datepicker').each(function(i, e) {
      var dates, disabler;
      dates = $(e).data('only');
      disabler = new DateDisabler(dates);
      return $(e).datepicker({
        beforeShowDay: disabler.beforeShowDay
      });
    });
  });

}).call(this);


  jQuery(function() {
    return $('.datepicker').each(function(i, e) {
      var dates, disabler;
      dates = $(e).data('only');
      disabler = new DateDisabler(dates);
      return $(e).datepicker({
        beforeShowDay: disabler.beforeShowDay
      });
    });
  });

}).call(this);