Fall-back support for XMLHTTPRequest - javascript

We have a web application that makes use of native XMLHttpRequest() to send data back to our server. One of our larger clients have users that appear to be running IE8 in Win7 (64-bit) and have "Enable native XMLHTTP support" disabled in their browser.
We've implemented the typical scenario of instantiating an ActiveXObject in place of XMLHttpRequest in order to try to support the likes if IE6 (no native XMLHTTP support; yes, we still have clients running this on thin clients!) which I am hoping IE8 can utilise as a fallback if this checkbox option has been switched off. However, once an object has been created, I get a type error when calling open() method on it.
Here's my code:
// Posts back an xml file synchronously and checks for parse error.
// Returns xml object or null. Used in RSUserData.
XML.PostXmlFile = function(sURL, doc)
{
try
{
// Validate Input
if ((typeof (sURL) != "string") || (sURL == ""))
return null;
if (window.XMLHttpRequest) // IE7+, FF and Chrome
{
// Mozilla, create a new DOMParser and parse from string
// Although IE9 and IE10 can successfully load XML using this block, it can't use document.evaluate nor selectNodes/selectSingleNode to navigate it
// Ref: http://msdn.microsoft.com/en-us/library/ie/ms535874(v=vs.85).aspx
// Ref: http://msdn.microsoft.com/en-us/library/ie/ms534370(v=vs.85).aspx
// Ref: http://blogs.msdn.com/b/ie/archive/2012/07/19/xmlhttprequest-responsexml-in-ie10-release-preview.aspx
var req = new XMLHttpRequest();
req.open("post", sURL, false);
req.send(doc);
if (req.status != 200)
throw { message: 'HTTP Post returned status ' + req.status + ' (' + req.statusText + ') when sending to ' + sURL };
// IE11+: req.responseXML returns a native XML Document
// IE9/10: req.responseXML returns an IXMLDOMDocument2 object but we can convert req.responseText to native XML using DOMParser
// IE6/7/8: req.responseXML returns an IXMLDOMDocument2 object but DOMParser is not available
if (window.DOMParser)
{
var parser = new DOMParser();
return parser.parseFromString(req.responseText, 'application/xml');
}
else
return req.responseXML; // NATIVE
}
else
{
// up to IE6:
// Ref: http://blogs.msdn.com/b/xmlteam/archive/2006/10/23/using-the-right-version-of-msxml-in-internet-explorer.aspx
var oXML = XML.GetActiveX_XML();
if (!oXML)
throw { message: "Could not instantiate an Msxml2 ActiveXObject", innerException: e };
oXML.open('POST', sURL, true);
oXML.send(sFile);
if (oXML.parseError.errorCode == 0)
{
xmlDoc = oXML;
return xmlDoc;
}
return null;
}
}
catch (e)
{
var s = "Exception in XML.PostXmlFile(). " + (e.message ? e.message : "");
throw { message: s, innerException: e };
}
}
XML.GetActiveX_XML = function()
{
var progIDs = ['Msxml2.DOMDocument.6.0', 'Msxml2.DOMDocument.3.0'];
for (var i = 0; i < progIDs.length; i++)
{
try
{
var oXML = new ActiveXObject(progIDs[i]);
var sl = oXML.getProperty("SelectionLanguage");
if (sl !== "XPath")
oXML.setProperty("SelectionLanguage", "XPath"); // Changes v3.0 from XSLPattern to XPath
var ns = "xmlns:rs='" + XML._nsResolver('rs') + "' xmlns:xsi='" + XML._nsResolver('xsi') + "'";
// ns = "xmlns:na='http://myserver.com' xmlns:nb='http://yourserver.com'";
oXML.setProperty("SelectionNamespaces", ns);
return oXML;
}
catch (ex) { }
}
return null;
}
NOTES:
The aim is to call to XML.PostXmlFile() with the url and payload.
Modern browsers use new XMLHttpRequest() as expected
IE6 is expected to use XML.GetActiveX_XML() on account that window.XMLHttpRequest returns falsey
IE8 with "Enable native XMLHTTP support" disabled falls through to the IE6 code (because window.XMLHttpRequest returns falsey) but the instantiated object fails because it doesn't support open() method (oXML.open('POST', sURL, true);)
Is there any way I can post my payload back using IE8 when "Enable native XMLHTTP support" is disabled?

You should see if the Microsoft.XMLHTTP is available before checking if there is a XMLHttpRequest:
var bActiveX;
try {
new ActiveXObject('Microsoft.XMLHTTP');
bActiveX = true;
}
catch(e) {
bActiveX = false;
}
And then, check in your if condition:
if (window.XMLHttpRequest || bActiveX) { // IE7+, FF and Chrome
var req = XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
/* the rest of your code */
}

Related

Retrieve URI of an XML DOM object using Internet Explorer

In Firefox and Chrome the documentURI property of the document node object of an XML DOM will return the URI of the DOM if it is created using the XMLHTTPRequest object.
Is there an equivalent property for the Internet Explorer DOM, and if so what is it? The documentURI, url, URL and baseURI properties all return either null or undefined.
The MSXML documentation for the url property made me hope that this would return the URL used in the HTTP request that created the DOM - but the example given doesn't use XMLHTTPRequest.
The code I've used to create the DOM and then test the property is below:
function getXslDom(url) {
if (typeof XMLHttpRequest == "undefined") {
XMLHttpRequest = function () {
return new ActiveXObject("Msxml2.XMLHTTP.6.0");
};
}
var req = new XMLHttpRequest();
req.open("GET", url, false);
req.send(null);
var status = req.status;
if (status == 200 || status == 0) {
return req.responseXML;
} else {
throw "HTTP request for " + url + " failed with status code: " + status;
}
};
var xslDom = getXslDom('help.xsl');
// the following shows "undefined" for IE
window.alert(xslDom.documentURI);
Using the example from the MSXML page you linked I managed to get it to work:
<script>
var getXslDom = function(url) {
if(typeof ActiveXObject === 'function') {
var xmlDoc = new ActiveXObject("Msxml2.DOMDocument.3.0");
xmlDoc.async = false;
xmlDoc.load(url);
if (xmlDoc.parseError.errorCode != 0) {
var myErr = xmlDoc.parseError;
throw "You have error " + myErr.reason;
} else {
return xmlDoc;
}
} else {
var req = new XMLHttpRequest();
req.open("GET", url, false);
req.send(null);
var status = req.status;
if (status == 200 || status == 0) {
return req.responseXML;
} else {
throw "HTTP request for " + url + " failed with status code: " + status;
}
}
}
var dom = getXslDom('help.xsl')
alert(dom.documentURI || dom.url)
</script>
Here is a demo.
Cheers!
PS: I used "alert" only because the OP seems to use it, personally I prefer "console.log", which I also recommend to the OP.

How do i link a xml file with several nodes and subnodes?

am looking for a javascript that will load an xml file and will display something like rectangules with links based on the xml child nodes, parents linked to childs and subnodes linked to nodes. how would i be able to do this?
You can accomplish this with AJAX.
First, create a function that will pull information from your XML file:
function loadXMLdoc(url) {
var ajaxRequest;
try {
// Opera 8.0+, Firefox, Safari
ajaxRequest = new XMLHttpRequest();
} catch(e) {
// Internet Explorer Browsers
try {
ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
} catch(e) {
try {
ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
} catch(e) {
// Something went wrong
alert("Your browser broke!");
return false;
}
}
}
// Create a function that will receive data sent from the server
ajaxRequest.onreadystatechange = function() {
if (ajaxRequest.readyState === 4) {
if (ajaxRequest.status === 200) {
// a hidden div to display the result
var result = document.getElementById('result');
result.style.display = 'block';
result.innerHTML = ajaxRequest.responseText;
} else {
result.innerHTML = 'An error has occurred making the request';
}
}
ajaxRequest.open("GET", url, true);
ajaxRequest.send();
};
}
From here, you can start grabbing data from your XML file. Inside your if (ajaxRequest.status === 200) { } statement, you can start calling elements:
var elem = ajaxRequest.responseXML.getElementById('elem');
var parents = elem.parentNodes;
var children = parents.childNodes;
It's up to you exactly how you'd like to format this and what data you're grabbing, but this should be a good starting point for you.

IE8 is breaking my AJAX... FF is fine

Feeling very proud of myself after creating a form with an AJAX submit, I test it in IE8 and get "Message: 'quantity' is undefined". I've read that it could be something to do with the fact that earlier versions of IE used ActiveX for AJAX requests, but I'm very new to JS and have no real understanding of the problem, let alone the ability to implement a fix.
Here's my code:
var time_variable;
function getXMLObject() //XML OBJECT
{
var xmlHttp = false;
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP") // For Old Microsoft Browsers
}
catch (e) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP") // For Microsoft IE 6.0+
}
catch (e2) {
xmlHttp = false // No Browser accepts the XMLHTTP Object then false
}
}
if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
xmlHttp = new XMLHttpRequest(); //For Mozilla, Opera Browsers
}
return xmlHttp; // Mandatory Statement returning the ajax object created
}
var xmlhttp = new getXMLObject(); //xmlhttp holds the ajax object
function ajaxFunction() {
var getdate = new Date(); //Used to prevent caching during ajax call
if(xmlhttp) {
var txtname = document.getElementById("txtname");
xmlhttp.open("POST","slots.php",true); //calling testing.php using POST method
xmlhttp.onreadystatechange = handleServerResponse;
xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlhttp.send("quantity=" + quantity.value + "&price=" + price.value + "&slot=" + slot.value + "&store=" + store.value); //Posting txtname to PHP File
}
}
function handleServerResponse() {
if (xmlhttp.readyState == 4) {
if(xmlhttp.status == 200) {
document.getElementById("message").innerHTML=xmlhttp.responseText; //Update the HTML Form element
}
else {
alert("Error during AJAX call. Please try again");
}
}
}
From your last comment on your question, I suspect you are not defining 'quantity' anywhere and assuming that it will reference the form field. Try this:
if(xmlhttp) {
var txtname = document.getElementById("txtname");
var quantity = document.getElementById("quantity");
var price = document.getElementById("price");
var store = document.getElementById("store");
xmlhttp.open("POST","slots.php",true); //calling testing.php using POST method
xmlhttp.onreadystatechange = handleServerResponse;
xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlhttp.send("quantity=" + quantity.value + "&price=" + price.value + "&slot=" + slot.value + "&store=" + store.value); //Posting txtname to PHP File
}
If quantity is a form field you need to get it using getElementById before using it just like you did with txtname:
var quantity = document.getElementById("quantity");
You cant use it directly from the form.

How do I force or add the content length for ajax type POST requests in Firefox?

I'm trying to POST a http request using ajax, but getting a response from the apache server using modsec_audit that: "POST request must have a Content-Length header." I do not want to disable this in modsec_audit.
This occurs only in firefox, and not IE. Further, I switched to using a POST rather than a GET to keep IE from caching my results.
This is a simplified version of the code I'm using for the request, I'm not using any javascript framework.
function getMyStuff(){
var SearchString = '';
/* build search string */
...
/* now do request */
var xhr = createXMLHttpRequest();
var RequestString = 'someserverscript.cfm' + SearchString;
xhr.open("POST", RequestString, true);
xhr.onreadystatechange = function(){
processResponse(xhr);
}
xhr.send(null);
}
function processResponse(xhr){
var serverResponse = xhr.responseText;
var container = document.getElementById('myResultsContainer');
if (xhr.readyState == 4){
container.innerHTML = serverResponse;
}
}
function createXMLHttpRequest(){
try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) {}
try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {}
try { return new XMLHttpRequest(); } catch(e) {}
return null;
}
How do I force or add the content length for ajax type POST requests in Firefox?
xhr.setRequestHeader("Content-Length", "0");
would be my best guess.
BTW, if you want to stop caching in IE, just add a random number onto the end, as in:
var RequestString = 'someserverscript.cfm' + SearchString + '&random=' + Math.random();
Try to actually send something instead of null (xhr.send(null);).

AJAX responseXML errors

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.
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,"<","<");
//text = replaceAll(text,">",">");
//text = replaceAll(text,""","\"");
//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.
This problem occurs mostly when content type is mis-detected by the browser or it's not sent correctly.
Its easier to just override it:
var request = new XMLHttpRequest();
request.open("GET", url, false);
request.overrideMimeType("text/xml");
request.send(null);
return request.responseXML;
Not sure why... This problem occurs only with Safari and Chrome (WebKit browsers, the server sends the headers correctly).
Are you calling the URL relative to the current document? Since IE would be using the ActiveXObject, it might need an absolute path, for example:
http://some.url/ConferenceRoomSchedules.xml
As for the XML, are you sure it's well-formed? Does it load in an XML editor, for instance?
What I can suggest you is to take a look at frameworks that hide and manage these cross-browser issues for you (in a reliable way). A good point here is jQuery. Doing these things yourself can become quite difficult and complex.
This may be what you need.
//Edit:
This is how the w3school shows it:
function ajaxFunction()
{
var xmlhttp;
if (window.XMLHttpRequest)
{
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else if (window.ActiveXObject)
{
// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
else
{
alert("Your browser does not support XMLHTTP!");
}
}
To avoid your cross browser problems (and save yourself coding a lot of items that a strong community has already developed, tested, and reviewed), you should select a javascript library. JQuery and Dojo are great choices.
I believe that your web server need to serve correct response headers with 'ConferenceRoomSchedules.xml' e.g. Content-Type: text/xml or any other xml type.
The answer provided by Aron in https://stackoverflow.com/a/2081466/657416 is from my point of view the simplest (and the best) one. Here is my working code:
ajax = ajaxRequest();
ajax.overrideMimeType("text/xml");
ajax.open("GET", myurl;

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