Patch

    var xmlhttp = new XMLHttpRequest();
    xmlhttp.onreadystatechange = function () {
        if (xmlhttp.readyState == XMLHttpRequest.DONE) {
            console.log(xmlhttp.responseText);
        }
    };
    xmlhttp.open('POST', 'your_url.ext', true);
    xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
    query = 'yourquerydata=foo';
    xmlhttp.setRequestHeader("Content-length", query.length);
    xmlhttp.send();