custom ajax

 var ajax = {};

ajax.send = function(url, cb_success, method, data, sync, cb_error) {
    var x = new XMLHttpRequest();
    x.open(method, url, sync);
    x.onreadystatechange = function() {
        if (x.readyState === 4 && x.status === 200) {
                    cb_success(x.responseText);
        } else {
        cb_error(x.statusText);
        }
    };
    if (method === 'POST') {
        x.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    }
    x.send(data)
};

ajax.get = function(url, data, cb_success, sync, cb_error) {
    var query = [];
    for (var key in data) {
        query.push(encodeURIComponent(key) + '=' + encodeURIComponent(data[key]));
    }
    ajax.send(url + '?' + query.join('&'), cb_success, 'GET', null, sync, cb_error);
};

ajax.post = function(url, data, cb_success, sync, cb_error) {
    var query = [];
    for (var key in data) {
        query.push(encodeURIComponent(key) + '=' + encodeURIComponent(data[key]));
    }
    ajax.send(url, cb_success, 'POST', query.join('&'), sync, cb_error);
};