Hi,

Try to create the XMLHttpRequest in the below mentioned format

 if (window.XMLHttpRequest) {
        portletReq = new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        portletReq = new ActiveXObject("Microsoft.XMLHTTP");
    }
    if(portletReq){
    portletReq.onreadystatechange = processReqChange;
    portletReq.open("GET", updateURL, true);
    portletReq.send();
    }else{
    alert("Not going inside");
    }