JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>datepicker demo</title>
  <link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/smoothness/jquery-ui.css">
  <script src="//code.jquery.com/jquery-1.12.4.js"></script>
  <script src="//code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
</head>
<body>
 
<div id="datepicker"></div>
 
<script>
$( "#datepicker" ).datepicker({
    dateFormat: 'dd/mm/yy',
    closeText:"Schließen",
    prevText:"Vorheriger",
    nextText:"Nächster;",
    currentText:"Heute",
    monthNames: ["Januar","Februar","März","April","Mai","Juni","Juli","August","September","Oktober","November","Dezember"],
    monthNamesShort:["Jan","Feb","Mar","Apr","Mai","Jun","Jul","Aug","Sep","Okt","Nov","Dez"],
        dayNames:["Sonntag","Montag","Dienstag","Mittwoch","Donnerstag","Freitag","Samstag"],
        dayNamesShort:["So","Mo","Di","Mi","Do","Fr","Sa"],
    dayNamesMin:["So","Mo","Di","Mi","Do","Fr","Sa"],
    weekHeader:"Sm",
    firstDay:1,
    beforeShowDay: (date)=>{
       var monthDays = new Date(date.getFullYear(),date.getMonth() + 1,0).getDate();
       var day = date.getDay();
       return [( (day==5 && date.getDate() > monthDays - 7 )), ''];
    }
});
</script>
 
</body>
</html>