AJAX responseXML errors

Question

I've been having some weird issues when it comes to make an AJAX request and handling the response.

I am making an ajax call for an xml file. however when i get the response the xhr.responseText property works fine in firefox but not in IE. Another thing is that I am trying to access the xhr.responseXML as XMLDocument, but it tells me in firefox it tells me that xhr.responseXML is undefined in ie it doesnt even show me the undefined error or displays the output.

This is the code I am using to make the request:

var ajaxReq = function(url, callback) {
    //initialize the xhr object and settings
    var xhr = window.ActiveXObject ?
            new ActiveXObject("Microsoft.XMLHTTP") : new XMLHttpRequest(),
    //set the successful connection function
        httpSuccess = function(xhr) {
            try {
                // IE error sometimes returns 1223 when it should be 204
                //  so treat it as success, see XMLHTTPRequest #1450
                // this code is taken from the jQuery library with some modification.
                return !xhr.status && xhr.status == 0 ||
                        (xhr.status >= 200 && xhr.status < 300) ||
                        xhr.status == 304 || xhr.status == 1223;
            } catch (e) { }
            return false;
        };

    //making sure the request is created
    if (!xhr) {
        return 404; // Not Found
    }


    //setting the function that is going to be called after the request is made
    xhr.onreadystatechange = function() {
        if (!httpSuccess(xhr)) {
            return 503; //Service Unavailable
        }
        if (xhr.responseXML != null && xhr.responseText != null &&
                xhr.responseXML != undefined && xhr.responseText != undefined) {
            callback(xhr);
        }
    };


    //open request call
    xhr.open('GET', url, true);

    //setup the headers
    try {
        xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        xhr.setRequestHeader("Accept", "text/xml, application/xml, text/plain");
    } catch ( ex ) {
        window.alert('error' + ex.toString());
    }

    //send the request
    try {
        xhr.send('');
    } catch (e) {
        return 400; //bad request
    }

    return xhr;
};

and this is how i am calling the function to test for results:

window.onload = function() {
    ajaxReq('ConferenceRoomSchedules.xml', function(xhr) {
        //in firefox this line works fine,
        //but in ie it doesnt not even showing an error
        window.document.getElementById('schedule').innerHTML = xhr.responseText;
        //firefox says ''xhr.responseXML is undefined'.
        //and ie doesn't even show error or even alerts it.
        window.alert(xhr.reponseXML.documentElement.nodeName);
    });
}

This is also my first attempt to work with AJAX so there might be something that I am not looking at right. I've been searching crazy for any indications of why or how to fix it, but no luck there. any ideas would be great.

EDIT:

I know this would be better with a framework, but the boss doesn't want to add a framework for just an ajax functionality ('just' is not a fair word for ajax :P). So I am doing it with pure javascript.

The XML file is well-formed, I see it well in the web browser, but for completion this is the testing file I am using:

<?xml version="1.0" encoding="utf-8"?>
<rooms>
  <room id="Blue_Room">
    <administrator>somebody@department</administrator>
    <schedule>
      <event>
        <requester>
          <name>Johnny Bravo</name>
          <email>jbravo@department</email>
        </requester>
        <date>2009/09/03</date>
        <start_time>11:00:00 GMT-0600</start_time>
        <end_time>12:00:00 GMT-0600</end_time>
      </event>
    </schedule>
  </room>
  <room id="Red_Room">
    <administrator>somebody@department</administrator>
    <schedule>
    </schedule>
  </room>
  <room id="Yellow_Room">
    <administrator>somebody@department</administrator>
    <schedule>
    </schedule>
  </room>
</rooms>

EDIT 2: Well the good news is that I convinced my boss to use jQuery, the bad news is that AJAX still perplexes me. I'll read more about it just for curiousity. Thanks for the tips and I gave the answer credit to Heat Miser because he was the closest working tip.

Answer 1

I was having the same problem a few years ago, then I gave up on responseXML and began always using responseText. This parsing function has always worked for me:

function parseXml(xmlText){
    try{
        var text = xmlText;
        //text = replaceAll(text,"&lt;","<");
        //text = replaceAll(text,"&gt;",">");
        //text = replaceAll(text,"&quot;","\"");
        //alert(text);
        //var myWin = window.open('','win','resize=yes,scrollbars=yes');
        //myWin.document.getElementsByTagName('body')[0].innerHTML = text;
        if (typeof DOMParser != "undefined") { 
            // Mozilla, Firefox, and related browsers 
            var parser=new DOMParser();
            var doc=parser.parseFromString(text,"text/xml");
            //alert(text);
            return doc; 
        }else if (typeof ActiveXObject != "undefined") { 
            // Internet Explorer. 
        var doc = new ActiveXObject("Microsoft.XMLDOM");  // Create an empty document 
            doc.loadXML(text);            // Parse text into it 
            return doc;                   // Return it 
        }else{ 
            // As a last resort, try loading the document from a data: URL 
            // This is supposed to work in Safari. Thanks to Manos Batsis and 
            // his Sarissa library (sarissa.sourceforge.net) for this technique. 
            var url = "data:text/xml;charset=utf-8," + encodeURIComponent(text); 
            var request = new XMLHttpRequest(); 
            request.open("GET", url, false); 
            request.send(null); 
            return request.responseXML; 
        }
    }catch(err){
        alert("There was a problem parsing the xml:\n" + err.message);
    }
}

With this XMLHttpRequest Object:

// The XMLHttpRequest class object

debug = false;

function Request (url,oFunction,type) {
    this.funct = "";
    // this.req = "";
    this.url = url;
    this.oFunction = oFunction;
    this.type = type;
    this.doXmlhttp = doXmlhttp;
    this.loadXMLDoc = loadXMLDoc;
}

function doXmlhttp() {
    //var funct = "";
    if (this.type == 'text') {
        this.funct = this.oFunction + '(req.responseText)';
    } else {
        this.funct = this.oFunction + '(req.responseXML)';
    }
    this.loadXMLDoc();
    return false;
}

function loadXMLDoc() {
    //alert(url);
    var functionA = this.funct;
    var req;
    req = false;

    function processReqChange() {
        // alert('reqChange is being called');
        // only if req shows "loaded"
        if (req.readyState == 4) {
            // only if "OK"
            if (req.status == 200) {
                // ...processing statements go here...
                eval(functionA);
                if(debug){
                    var debugWin = window.open('','aWindow','width=600,height=600,scrollbars=yes');
                    debugWin.document.body.innerHTML = req.responseText;
                }
            } else {
                alert("There was a problem retrieving the data:\n" +
                    req.statusText + '\nstatus: ' + req.status);
                if(debug){
                    var debugWin = window.open('','aWindow','width=600,height=600,scrollbars=yes');
                    debugWin.document.body.innerHTML = req.responseText;
                }
            }
            }
    }

    // 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;
        if(this.url.length > 2000){
            var urlSpl = this.url.split('?');
            req.open("POST",urlSpl[0],true);
            req.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
            req.send(urlSpl[1]);
        } else {
            req.open("GET", this.url, true);
            req.send("");
        }
    }
}

function browserSniffer(){
    if(navigator.userAgent.toLowerCase().indexOf("msie") != -1){
        if(navigator.userAgent.toLowerCase().indexOf("6")){
            return 8;
        }else{
            return 1;
        }
    }
    if(navigator.userAgent.toLowerCase().indexOf("firefox") != -1){
        return 2;
    }
    if(navigator.userAgent.toLowerCase().indexOf("opera") != -1){
        return 3;
    }
    if(navigator.userAgent.toLowerCase().indexOf("safari") != -1){
        return 4;
    }
    return 5;
}

Granted, this is very old code, but it is still working for me on a site I built a few years ago. I agree with everyone else though I typically use a framework nowadays so I don't have to use this code or anything like it anymore.

You can ignore some of the particulars with the split, etc... in the Request onreadystate function. It was supposed to convert the request to a post if it was longer than a certain length, but I just decided it was always better to do a post.