JSFiddle - React, Tailwind, and code Playground

HTML

<button class="btnUploadFile">
Upload
</button>

JavaScript

/**
* Ajax upload
* Project page - http://valums.com/ajax-upload/
* Copyright (c) 2008 Andris Valums, http://valums.com
* Licensed under the MIT license (http://valums.com/mit-license/)
* Version 3.6 (26.06.2009)
*/

/**
* Changes from the previous version:
* 1. Fixed minor bug where click outside the button
* would open the file browse window
* 
* For the full changelog please visit: 
* http://valums.com/ajax-upload-changelog/
*/

(function () {

    var d = document, w = window;

    /**
    * Get element by id
    */
    function get(element) {
        if (typeof element == "string")
            element = d.getElementById(element);
        return element;
    }

    /**
    * Attaches event to a dom element
    */
    function addEvent(el, type, fn) {
        if (w.addEventListener) {
            el.addEventListener(type, fn, false);
        } else if (w.attachEvent) {
            var f = function () {
                fn.call(el, w.event);
            };
            el.attachEvent('on' + type, f)
        }
    }


    /**
    * Creates and returns element from html chunk
    */
    var toElement = function () {
        var div = d.createElement('div');
        return function (html) {
            div.innerHTML = html;
            var el = div.childNodes[0];
            div.removeChild(el);
            return el;
        }
    } ();

    function hasClass(ele, cls) {
        return ele.className.match(new RegExp('(\\s|^)' + cls + '(\\s|$)'));
    }
    function addClass(ele, cls) {
        if (!hasClass(ele, cls)) ele.className += " " + cls;
    }
    function removeClass(ele, cls) {
        var reg = new RegExp('(\\s|^)' + cls + '(\\s|$)');
        ele.className = ele.className.replace(reg, ' ');
    }

    // getOffset function copied from jQuery lib (http://jquery.com/)
    if (document.documentElement["getBoundingClientRect"]) {
        // Get Offset using getBoundingClientRect
        // http://ejohn.org/blog/getboundingclientrect-is-awesome/
        var...