function createXmlRequest() {
     var req = null;
     
     if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
     } else if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
     }    
          
     return req;
}

function isAjax(req){
    if (req.readyState == 4){
        if (req.status == 200){
            return true;
        }    
    }    
}