JSFiddle - React, Tailwind, and code Playground

HTML

<p>Date: <input type="text" class="calendar" /></p>
<form id="form">
  
<form>

JavaScript

$(function() {
   $( '.calendar' ).datepicker(
    {
        dateFormat: 'dd.mm.yy',
        numberOfMonths: 1,
        onSelect: function (dateText, inst) {
            $("#form").append('<input type="hidden" name="date" value="'+ dateText +'">');
            $.ajax({
                    url:"/echo/html/",          // give your url
                    data: $("#form").serialize(),
                    success: function(data)  
                  {
                    alert('success'); // optional
                   }
           });
        },

    });
     $( '.calendar' ).datepicker( regionalIs ).datepicker('refresh');
  });