Vanilla javascript XHR request to ipinfo.io

ipinfo.js

function ipinfo(cb, ip) {
    var request;
    if (window.XMLHttpRequest) { // Mozilla, Safari, ...
        request = new XMLHttpRequest();
    } else if (window.ActiveXObject) { // IE
        try {
            request = new ActiveXObject('Msxml2.XMLHTTP');
        } catch (e) {
            try {
                request = new ActiveXObject('Microsoft.XMLHTTP');
            } catch (e) {}
        }
    }
    request.open("GET", '//ipinfo.io/' + ((ip) ? ip : ''), false);
    request.setRequestHeader("Accept", "application/json");
    request.onreadystatechange = function() {
        if (request.readyState == 4 && request.status == 200) {
            cb(request.responseText);
        }
    };
    request.send(null);
}

ipinfo(function(response) {
    console.log(response);
});

Hi.. Chrome alerts "Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience."