new XMLHttpRequest()

var xhr = new XMLHttpRequest();

xhr.open('POST', 'http://www.site.com/', true, 'username', 'password');

xhr.withCredentials = true;

xhr.timeout = 120000;

xhr.setRequestHeader('My-Header', '123');

xhr.overrideMimeType('text/plain; charset=x-user-defined');

xhr.onreadystatechange = function () {
    if (xhr.readyState === 4) {
        if (xhr.status === 200 || xhr.status === 0) {
            console.log('status: ' + xhr.status === 1223 ? 204 : xhr.status);
            console.log('statusText: ' + xhr.status === 1223 ? 'No Content' : xhr.statusText);
            console.log('getAllResponseHeaders: ' + xhr.getAllResponseHeaders());
            console.log('getResponseHeader: ' + xhr.getResponseHeader('Content-Type'));
            console.log('responseText: ' + xhr.responseText);
        } else {
            console.log('Error in request.');
        }
    }
};

xhr.onabort = function () {
    if (!xhr) {return;}
    xhr = null;
    console.log('Aborted.');
};

xhr.ontimeout = function () {
    xhr = null;
    console.log('Timeout.');
};

xhr.onerror = function (error) {
    xhr = null;
    console.log('Error.');
    console.log(error.message);
};

xhr.send(JSON.stringify({a: 1, b: 2}));

setTimeout(function () {
    if (xhr) {xhr.abort();}
}, 1000);