var cb_req;

function cb_navigate(month,year) {
        var url = "/func/cb_calendar.php?month="+month+"&year="+year;
        if(window.XMLHttpRequest) {
                cb_req = new XMLHttpRequest();
        } else if(window.ActiveXObject) {
                cb_req = new ActiveXObject("Microsoft.XMLHTTP");
        }
        cb_req.open("GET", url, true);
        cb_req.onreadystatechange = cb_callback;
        cb_req.send(null);
}

function cb_callback() {
        if(cb_req.readyState == 4) {
                if(cb_req.status == 200) {
                        response = cb_req.responseText;
                        document.getElementById("cb_calendar").innerHTML = response;
                } else {
                        alert("There was a problem retrieving the data:\n" + cb_req.statusText);
                }
        }
}