JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.15.1/moment.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/fullcalendar/3.0.0/fullcalendar.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/fullcalendar/3.0.0/fullcalendar.js"></script>
<div id='calendar'>
</div>

JavaScript

document.addEventListener('DOMContentLoaded', function() {
    $('#calendar').fullCalendar({
        eventAfterAllRender: function(view) {
            makeTodayButtonActive();
        }
    });

    function makeTodayButtonActive() {
        $('#calendar button.fc-today-button').removeClass('fc-state-disabled').prop('disabled', false);
    }
});