JSFiddle - React, Tailwind, and code Playground

JavaScript

var xmlhttp = null;
if (window.XMLHttpRequest) { // code for Firefox, Opera, IE7, etc.
    xmlhttp = new XMLHttpRequest();
} else if (window.ActiveXObject) { // code for IE6, IE5
    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
if (xmlhttp != null) {
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4) { // 4 = "loaded"
            if (xmlhttp.status == 200) { // 200 = "OK"
                console.log('reponse is:', xmlhttp.responseText);
            } else {
                console.log('oops, an error occured, xhr is: ', xmlhttp);
            }
        }
    }
    xmlhttp.open("POST", '/echo/html/', true);
    xmlhttp.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
    xmlhttp.send("html=jó öreg ajax, de azért ezt kerüljük..:)");
} else {
    alert("This is a not supported browser / Az ön böngészője nem támogatott! Please contact with the system administrator / Kérem konzultáljon a rendszergazdával!");
}