function getResponse() {
               document.getElementById("_receivedMsgLabel").innerHTML += "getResponse() called.
";
               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!
";
                   var status = receiveReq.status;
                                       var txt = receiveReq.responseText;
                                       document.getElementById("_receivedMsgLabel").innerHTML += txt + "
";
                   
                   mTimer = setTimeout("getResponse();", 0);
               }

               getResponse();
           }

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?