JSFiddle - React, Tailwind, and code Playground

JavaScript

var nextAd;

function addEvent(object, evName, fnName, cap) {
    if (object.attachEvent) object.attachEvent("on" + evName, fnName);
    else if (object.addEventListener) object.addEventListener(evName, fnName, cap);
}

function makeBannerAds() {
    var bannerBox = document.createElement("div");
    bannerBox.id = "bannerBox";
    document.body.appendChild(bannerBox);
    for (var i = 0; i < adsURL.length; i++) {
        console.log("Iteration: " + i)
        var bannerAd = document.createElement("div");
        bannerAd.className = "bannerAd";
        bannerAd.style.zIndex = i;
        var urlLink = document.createElement("a");
        urlLink.href = adsURL[i];
        var bannerIndex = document.createElement("img");
        bannerIndex.src = "banner" + i + ".jpg";
        bannerIndex.style.width = "290px";
        bannerIndex.style.height = "55px";
        bannerBox.appendChild(bannerAd);
    }
    bannerBox.appendChild(bannerAd);
    setInterval(changeBannerAd(), 10000);
}

var changeBannerAd = function () {
    var allAds = document.getElementById("bannerBox").childNodes;
    alert('work');
    for (var i = 0; i < num; i++) {
        if (allAds.style.zIndex == 0) {
            allAds.style.top = "-50px";
            nextAd = allAds;
        }
    }

    for (var i = 0; i < num; i++) {
        allAds.style.zIndex--;

        if (allAds.style.zIndex < 0) allAds.style.zIndex = num - 1;
    }

    var timeDelay = 0;
    for (var i = -50; i <= 0; i++) {
        setTimeout(moveNextAd(" + i + "), timeDelay);
        timeDelay += 15;
    }
}

var moveNextAd = function (top) {
    nextAd.style.top = top + ".px"
}

addEvent(window, "load", makeBannerAds(), false);

var adsURL = (function () {
    //this stores each item in the array using a index place holder
    adsURL = new Array();
    adsURL[0] = "testpage0.htm";
    adsURL[1] = "testpage1.htm";
    adsURL[2] = "testpage2.htm";
    adsURL[3] = "testpage3.htm";
    adsURL[4] = "testpage4.htm";
    adsURL[5] =...