XmlHttpRequest AJAX not returning message from COMET server

Question

I have the following COMET client javascript code:
function getResponse() {
document.getElementById("_receivedMsgLabel").innerHTML += "getResponse() called.<br/>";
if (receiveReq.readyState == 4 || receiveReq.readyState == 0) {
receiveReq.open("GET", "http://L45723:1802?callback=testcallback", true); //must use this URL at work.
receiveReq.onreadystatechange = handleReceiveMessage;
alert("handleReceiveMessage assigned to onreadystatechange event.");
receiveReq.overrideMimeType("text/x-json");
receiveReq.timeout = 100000;
var currentDate = new Date();
var sendMessage = JSON.stringify({
SendTimestamp: currentDate,
Message: "Message 1",
Browser: navigator.appName,
OriginUrl: document.URL
var sendMessage = "SendTimestamp=" + currentDate + "&Message=Message1&Browser=" + navigator.userAgent;
alert("JSON message created. About to send...");
receiveReq.send(sendMessage);
alert("Message sent.");
//function for handling the return message from Comet
function handleReceiveMessage() {
document.getElementById("_receivedMsgLabel").innerHTML += "Status=" + receiveReq.status;
document.getElementById("_receivedMsgLabel").innerHTML += "responseText=" + receiveReq.responseText;
if (receiveReq.readyState == 4 && receiveReq.status == 200) {
document.getElementById("_receivedMsgLabel").innerHTML += "Message received!<br/>";
var status = receiveReq.status;
var txt = receiveReq.responseText;
document.getElementById("_receivedMsgLabel").innerHTML += txt + "<br/>";
mTimer = setTimeout("getResponse();", 0);
getResponse();
The GET request is sent and received by the COMET server, which sends the response back when I choose to. The handleReceiveMessage() function is called, but the message the server sent is not in the xmlHttpRequest.responseText property.
Why?

Answer 1

I suggest continuing the discussion in your thread on mozillaZine, since this site focuses more on end-user support.
[http://forums.mozillazine.org/viewtopic.php?f=25&t=2480435 xmlHttpRequest object - mozillaZine Forums]