HTTPRequest = function(){
    var xmlhttp = null;
    try{
        xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch(_e){

        try{
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        catch(_E){}
    }
    if(!xmlhttp && typeof XMLHttpRequest != 'undefined'){
        try{
            xmlhttp = new XMLHttpRequest();
        }
        catch(_e){
            xmlhttp = false;
        }
    }
    return xmlhttp;
}//end block HttpRequest

//三级连动
function SelType(value,url)
{
    var date = new Date();
    var time = date.getTime();
    var http  = new HTTPRequest();
    http.open("GET",""+ url +"?Id="+ value +"&time=" + time ,true);
    http.onreadystatechange = function()
    {
    handleHttpResponse(http);
    }
    http.send(null); 
}
function handleHttpResponse(http)
{
    if(http.readyState == 4)
    {
        if(http.Status == 200)
        {
            var str = http.responseText;
            FillSelCity(str);
        }
    }
}