JSFiddle - React, Tailwind, and code Playground

JavaScript

(function() {

    var running = {};

    function noop() {}

    function handler() {
        if (this.readyState === 4) {
            (running[this.id][this.status === 200 ? "onsuccess" : "onerror"] || noop).call(this);
            delete running[this.id];
        }
    }

    window.send = function(url, method, data, onsuccess, onerror) {
        var req = new XMLHttpRequest();
        req.open(method, url, true);
        req.onreadystatechange = handler;
        req.send(data);
        req.id = (Math.random() * 1e5 | 0).toString(32);
        running[req.id] = {
            "onsuccess": onsuccess,
            "onerror": onerror
        };
    }
})();

send("/echo/html/", "POST", "html=World!", function(){ alert("Hello, " + this.responseText) });