ajax

var xhr = createStandardXHR() || createActiveXHR();
var state = 0;
xhr.onreadystatechange = function () {
    if (xhr.readyState == 4 && xhr.status == 200) {
        state = 1;
        typeof cb == 'function' && cb(undefined, dataType == 'json' ? JSON.parse(xhr.responseText) : xhr.responseText);
    } else {
        typeof cb == 'function' && cb(xhr.error);
        state = 2;
    }
}
setTimeout(function () {
    if (state == 0) {
        xhr.abort();
        typeof cb == 'function' && cb('timeout');
    }
}, 8000);
xhr.open('GET', url, true);
xhr.send();