JSFiddle - React, Tailwind, and code Playground

JavaScript

function loadAJAX() {
    function readyStateSwitch() {
        console.log(ajaxRequest.readyState);
    }
    var ajaxRequest = new XMLHttpRequest();
    ajaxRequest.onreadystatechange = readyStateSwitch; //passes a func reference
    ajaxRequest.open("GET", "/", true); //changed URL so that jsfiddle doesn't 404
    ajaxRequest.send();
}

loadAJAX();