JSFiddle - React, Tailwind, and code Playground

HTML

<div id="slider"></div>

JavaScript

var Klimateka = {
    Slider: function () {
        // Check if we have a slider div on page
        var slider = document.getElementById('slider');
        if (slider != null) {
            var images = ["slide-image-1.jpg", "slide-image-2.jpg", "slide-image-3.jpg", "slide-image-4.jpg"];
            var i = images.length;
            while (i) {
                i -= 1;
                var img = document.createElement("img");
                img.src = "images/" + images[i];
                slider.appendChild(img);
            }
            var d = document, imgs = new Array(), zInterval = null, current = 0, pause = false;
            imgs = d.getElementById("slider").getElementsByTagName("img");
            for (i = 1; i < imgs.length; i++) imgs[i].xOpacity = 0;
            imgs[0].style.display = "block";
            imgs[0].xOpacity = .99;

            setTimeout(xfade, 3500);

            function xfade() {
                cOpacity = imgs[current].xOpacity;
                nIndex = imgs[current + 1] ? current + 1 : 0;

                nOpacity = imgs[nIndex].xOpacity;

                cOpacity -= .05;
                nOpacity += .05;

                imgs[nIndex].style.display = "block";
                imgs[current].xOpacity = cOpacity;
                imgs[nIndex].xOpacity = nOpacity;

                setOpacity(imgs[current]);
                setOpacity(imgs[nIndex]);

                if (cOpacity <= 0) {
                    imgs[current].style.display = "none";
                    current = nIndex;
                    setTimeout(xfade, 3500);
                } else {
                    setTimeout(xfade, 50);
                }

                function setOpacity(obj) {
                    if (obj.xOpacity > .99) {
                        obj.xOpacity = .99;
                        return;
                    }
                    obj.style.opacity = obj.xOpacity;
                    obj.style.MozOpacity = obj.xOpacity;
                    obj.style.filter...