function ajax(url, target) {
    // native XMLHttpRequest object
    document.getElementById(target).innerHTML = '';
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
        req.onreadystatechange = function() {
            ajaxDone(target);
        };
        req.open("GET", url, true);
        req.send(null);
        // IE/Windows ActiveX version
    } else if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
        if (req) {
            req.onreadystatechange = function() {
                ajaxDone(target);
            };
            req.open("GET", url, true);
            req.send();
        }
    }
}

function ajaxDone(target) {
    // only if req is "loaded"
    if (req.readyState == 4) {
        // only if "OK"
        if (req.status == 200 || req.status == 304) {
            results = req.responseText;
            document.getElementById(target).innerHTML = results;
        } else {
            document.getElementById(target).innerHTML = "error:\n" + req.statusText;
        }
    }
}