XHR no connection wrapper

xhr.js

        var req = new XMLHttpRequest();
        req.open("post", 'https://jquery.com', true);
        req.onreadystatechange = function receiveResponse() {
console.log('readyState: ', this.readyState);
console.log('status: ', this.status);
console.log('response: ', this.response.length);

            if (this.readyState == 4) {
                if (this.status === 0 && this.response.length === 0) {
                    return console.log('NO CON')
                } else {
                     console.log("We go a response");
                }
            }
        };
        req.send();
        req = null;