var req;

function loadXMLDoc(url) {
	req = false;
    // branch for native XMLHttpRequest object
    if(window.XMLHttpRequest) {
    	try {
			req = new XMLHttpRequest();
        }
        catch(e) {
			req = false;
        }
    // branch for IE/Windows ActiveX version
    }
    else if(window.ActiveXObject) {
       	try {
        	req = new ActiveXObject("Msxml2.XMLHTTP");
      	}
      	catch(e) {
        	try {
          		req = new ActiveXObject("Microsoft.XMLHTTP");
        	}
        	catch(e) {
          		req = false;
        	}
		}
    }
	if(req) {
		req.onreadystatechange = processReqChange;
		req.open("GET", url, false);
		req.send("");
	}
}

function processReqChange() {
    // only if req shows "loaded"
    if (req.readyState == 4) {
        // only if "OK"
        if (req.status == 200) {
            // ...processing statements go here...
        }
        else {
            alert("There was a problem retrieving the XML data:\n" +
                req.statusText);
        }
    }
}