code: function() {
  
      var sizing = decideCalendarSize(getConfig().fullcalendar.defaultView);
  
      var args = {
        height: sizing.height,
        eventClick: clickTimeslot,
        windowResize: function() {
          var sizing = decideCalendarSize();
          calendarTarget.fullCalendar('changeView', sizing.view);
          calendarTarget.fullCalendar('option', 'height', sizing.height);
        }
      };
  
      $.extend(true, args, getConfig().fullcalendar);
      args.defaultView = sizing.view;
  
      calendarTarget = $('<div class="bookingjs-calendar empty-calendar">');
      rootTarget.append(calendarTarget);
  
      calendarTarget.fullCalendar(args);
  
      $(rootTarget).on('customer-timezone-changed', function () {
        if (!calendarTarget) return
        getAvailability();
        calendarTarget.fullCalendar('option', 'now', moment().tz(customerTimezone).format());
      })
  
      utils.doCallback('fullCalendarInitialized');
  
    }
docs: Setup and render FullCalendar