JSFiddle - React, Tailwind, and code Playground

HTML

<div id="datepicker" class="public-holiday-date-pick">
</div>

<select class="form-control" id="appointment_date" name="appointment[date]">
  <option value="">Veuillez chosir une date</option>
</select>

JavaScript

$(function() {
  $("#datepicker").datepicker({
    dateFormat: 'mm-dd-yy',
  });
});

$(window).load(function() {
  $("#datepicker").change(function() {
    var xxx = new Date($("#datepicker").val());
    var trigdate = $("#datepicker").val();
    var lundi = ["5", "6"];
    var mardi = ["5", "6"];
    var mercredi = ["5", "6"];
    var jeudi = ["5", "6"];
    var vendredi = ["5", "6"];
    var samedi = ["5", "6"];
    var dimanche = ["5", "6"];
    var option = '';
    var day = xxx.getDate();
    var month = xxx.getMonth() + 1;
    var year = xxx.getFullYear();
    var trigdate = year + "/" + month + "/" + day;
    switch (xxx.getDay()) {

      case 1:
        for (var i = 0; i < lundi.length; i++) {
          option += '<option value="' + trigdate + " à " + lundi[i] + "h" + '">' + lundi[i] + "h" + '</option>';
        }
        $('#appointment_date').find('option').remove()
        $('#appointment_date').append(option);
        break;
      case 2:
        for (var i = 0; i < mardi.length; i++) {
          option += '<option value="' + trigdate + " à " + mardi[i] + "h" + '">' + mardi[i] + "h" + '</option>';
        }
        $('#appointment_date').find('option').remove()
        $('#appointment_date').append(option);
        break;
      case 3:
        for (var i = 0; i < mercredi.length; i++) {
          option += '<option value="' + trigdate + " à " + mercredi[i] + "h" + '">' + mercredi[i] + "h" + '</option>';
        }
        $('#appointment_date').find('option').remove()
        $('#appointment_date').append(option);
        break;
      case 4:
        for (var i = 0; i < jeudi.length; i++) {
          option += '<option value="' + trigdate + " à " + jeudi[i] + "h" + '">' + jeudi[i] + "h" + '</option>';
        }
        $('#appointment_date').find('option').remove()
        $('#appointment_date').append(option);
        break;
      case 5:
        for (var i = 0; i < vendredi.length; i++) {
          option += '<option value="' + trigdate + " à " +...