How to change background color of selected date in FullCalendar

Question

I am trying to change the background color of the selected date in my calendar. In my below code, it highlights all the clicked date, how can I only highlight the last clicked date?

dayClick: function (day){
  var mydate = new Date(this[0].getAttribute("data-date"));
  var dateArray = mydate.toDateString().split(" ");
  document.querySelectorAll(".calendar-mobile p")[0].innerHTML = j_monthNames[mydate.getMonth()] + " " + mydate.getDate() + "日" + "(" + j_dayNames[dateArray[0].toLocaleLowerCase()] + ")";
  document.body.classList.remove("calendar-open");

  $month = '' + (mydate.getMonth() + 1);
  $day = '' + mydate.getDate();
  $year = mydate.getFullYear();

  if ($month.length < 2) $month = '0' + $month;
  if ($day.length < 2) $day = '0' + $day;
  $dates = [$year, $month, $day].join('-');
  $('[data-date='+$dates+']').css({"color": "red", "backgroundColor": "yellow",});
},

Answer 1

I have finally solved it this way:

$(document).ready(function() {
  $('#calendars').fullCalendar({
    header: {
      left: 'prev',
      center: 'title',
      right: 'next'
    },
    selectable: true,
  });
});

.fc-highlight {
  background: green !important;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/fullcalendar/3.0.1/fullcalendar.min.css" defer/>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.16.0/moment.min.js" defer></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/fullcalendar/3.0.1/fullcalendar.min.js" defer></script>
<div id="calendars"></div>

Just triggered the .fc-highlight class and it does the trick.