JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.js"></script>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.16/jquery-ui.min.js"></script>
    <link rel="stylesheet" type="text/css" media="screen" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.16/themes/base/jquery-ui.css">
<script type="text/javascript">
$(function() {   
    var startDate;
    var endDate;

    var selectCurrentWeek = function () {
        window.setTimeout(function () {
            $('.ui-weekpicker').find('.ui-datepicker-current-day a').addClass('ui-state-active').removeClass('ui-state-default');
        }, 1);
    }

    var setDates = function (input) {
        var $input = $(input);
        var date = $input.datepicker('getDate');
        if (date !== null) {
            var firstDay = $input.datepicker( "option", "firstDay" );
            var dayAdjustment = date.getDay() - firstDay;
            if (dayAdjustment < 0) {
                dayAdjustment += 7;
            }
            startDate = new Date(date.getFullYear(), date.getMonth(), date.getDate() - dayAdjustment);
            endDate = new Date(date.getFullYear(), date.getMonth(), date.getDate() - dayAdjustment + 6);
    
            var inst = $input.data('datepicker');
            var dateFormat = inst.settings.dateFormat || $.datepicker._defaults.dateFormat;
            $('#startDate').text($.datepicker.formatDate(dateFormat, startDate, inst.settings));
            $('#endDate').text($.datepicker.formatDate(dateFormat, endDate, inst.settings));
        }
    }

    $('.week-picker').datepicker({
        beforeShow: function () {
            $('#ui-datepicker-div').addClass('ui-weekpicker');
            selectCurrentWeek();
        },
        onClose: function...