根据选择查找地址

Question

function createREQ() {
    try {
        req = new XMLHttpRequest();
    } catch(err1) {
        try {
            req = new ActiveXObject("Msxm12.XMLHTTP");
        } catch(err2) {
            try {
                req = new ActiveXObject("Microsoft.XMLHTTP");
            } catch(err3) {
                req = false;
            }
        }
    }
    return req;
}

function requestGET(url, query, req) {
    myRand = parseInt(Math.random()*99999999);
    req.open("GET", url + '?' + query + '&rand=' + myRand, true);
    req.send(null);
}

function requestPOST(url, query, req) {
    req.open("POST", url, true);
    req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    req.send(query);
}

function doCallback(callback, item) {
    eval(callback + '(item)');
}

function doAjax(url, query, callback, reqtype, getxml) {
    var myreq = createREQ();
    myreq.onreadystatechange = function() {
        if (myreq.readyState == 4) {
            if (myreq.status == 200) {
                var item = myreq.responseText;
                if (getxml == 1) {
                    item = myreq.responseXML;
                }
                doCallback(callback, item);
            }
        }
    }
    if (reqtype == 'post') {
        requestPOST(url, query,myreq);
    } else {
        requestGET(url, query,myreq);
    }
}

/* Used for Find Your Sales Rep Page */
function cback1(text) { 
    document.getElementById('counties').innerHTML = text;
    document.getElementById('reps').innerHTML = "";
}
function cback2(text) {
    document.getElementById('reps').innerHTML = text;
}

仍然无法得到结果，请指导。