Develop Reference

.fail() fails to execute when ajax request is not successful [duplicate]

Is it possible to catch an error when using JSONP with jQuery? I've tried both the $.getJSON and $.ajax methods but neither will catch the 404 error I'm testing. Here is what I've tried (keep in mind that these all work successfully, but I want to handle the case when it fails):
jQuery.ajax({
type: "GET",
url: handlerURL,
dataType: "jsonp",
success: function(results){
alert("Success!");
},
error: function(XMLHttpRequest, textStatus, errorThrown){
alert("Error");
}
});
And also:
jQuery.getJSON(handlerURL + "&callback=?",
function(jsonResult){
alert("Success!");
});
I've also tried adding the $.ajaxError but that didn't work either:
jQuery(document).ajaxError(function(event, request, settings){
alert("Error");
});

Here's my extensive answer to a similar question.
Here's the code:
jQuery.getJSON(handlerURL + "&callback=?",
function(jsonResult){
alert("Success!");
})
.done(function() { alert('getJSON request succeeded!'); })
.fail(function(jqXHR, textStatus, errorThrown) { alert('getJSON request failed! ' + textStatus); })
.always(function() { alert('getJSON request ended!'); });

It seems that JSONP requests that don't return a successful result never trigger any event, success or failure, and for better or worse that's apparently by design.
After searching their bug tracker, there's a patch which may be a possible solution using a timeout callback. See bug report #3442. If you can't capture the error, you can at least timeout after waiting a reasonable amount of time for success.

Detecting JSONP problems
If you don't want to download a dependency, you can detect the error state yourself. It's easy.
You will only be able to detect JSONP errors by using some sort of timeout. If there's no valid response in a certain time, then assume an error. The error could be basically anything, though.
Here's a simple way to go about checking for errors. Just use a success flag:
var success = false;
$.getJSON(url, function(json) {
success = true;
// ... whatever else your callback needs to do ...
});
// Set a 5-second (or however long you want) timeout to check for errors
setTimeout(function() {
if (!success)
{
// Handle error accordingly
alert("Houston, we have a problem.");
}
}, 5000);
As thedawnrider mentioned in comments, you could also use clearTimeout instead:
var errorTimeout = setTimeout(function() {
if (!success)
{
// Handle error accordingly
alert("Houston, we have a problem.");
}
}, 5000);
$.getJSON(url, function(json) {
clearTimeout(errorTimeout);
// ... whatever else your callback needs to do ...
});
Why? Read on...
Here's how JSONP works in a nutshell:
JSONP doesn't use XMLHttpRequest like regular AJAX requests. Instead, it injects a <script> tag into the page, where the "src" attribute is the URL of the request. The content of the response is wrapped in a Javascript function which is then executed when downloaded.
For example.
JSONP request: https://api.site.com/endpoint?this=that&callback=myFunc
Javascript will inject this script tag into the DOM:
<script src="https://api.site.com/endpoint?this=that&callback=myFunc"></script>
What happens when a <script> tag is added to the DOM? Obviously, it gets executed.
So suppose the response to this query yielded a JSON result like:
{"answer":42}
To the browser, that's the same thing as a script's source, so it gets executed. But what happens when you execute this:
<script>{"answer":42}</script>
Well, nothing. It's just an object. It doesn't get stored, saved, and nothing happens.
This is why JSONP requests wrap their results in a function. The server, which must support JSONP serialization, sees the callback parameter you specified, and returns this instead:
myFunc({"answer":42})
Then this gets executed instead:
<script>myFunc({"answer":42})</script>
... which is much more useful. Somewhere in your code is, in this case, a global function called myFunc:
myFunc(data)
{
alert("The answer to life, the universe, and everything is: " + data.answer);
}
That's it. That's the "magic" of JSONP. Then to build in a timeout check is very simple, like shown above. Make the request and immediately after, start a timeout. After X seconds, if your flag still hasn't been set, then the request timed out.

I know this question is a little old but I didn't see an answer that gives a simple solution to the problem so I figured I would share my 'simple' solution.
$.getJSON("example.json", function() {
console.log( "success" );
}).fail(function() {
console.log( "error" );
});
We can simply use the .fail() callback to check to see if an error occurred.
Hope this helps :)

If you collaborate with the provider, you could send another query string parameter being the function to callback when there's an error.
?callback=?&error=?
This is called JSONPE but it's not at all a defacto standard.
The provider then passes information to the error function to help you diagnose.
Doesn't help with comm errors though - jQuery would have to be updated to also callback the error function on timeout, as in Adam Bellaire's answer.

Seems like this is working now:
jQuery(document).ajaxError(function(event, request, settings){
alert("Error");
});

I use this to catch an JSON error
try {
$.getJSON(ajaxURL,callback).ajaxError();
} catch(err) {
alert("wow");
alert("Error : "+ err);
}
Edit: Alternatively you can get the error message also. This will let you know what the error is exactly. Try following syntax in catch block
alert("Error : " + err);

Mayby this works?
.complete(function(response, status) {
if (response.status == "404")
alert("404 Error");
else{
//Do something
}
if(status == "error")
alert("Error");
else{
//Do something
}
});
I dont know whenever the status goes in "error" mode. But i tested it with 404 and it responded

you ca explicitly handle any error number by adding this attribute in the ajax request:
statusCode: {
404: function() {
alert("page not found");
}
}
so, your code should be like this:
jQuery.ajax({
type: "GET",
statusCode: {
404: function() {
alert("page not found");
}
},
url: handlerURL,
dataType: "jsonp",
success: function(results){
alert("Success!");
},
error: function(XMLHttpRequest, textStatus, errorThrown){
alert("Error");
}
});
hope this helps you :)

I also posted this answer in stackoverflow - Error handling in getJSON calls
I know it's been a while since someone answerd here and the poster probably already got his answer either from here or from somewhere else. I do however think that this post will help anyone looking for a way to keep track of errors and timeouts while doing getJSON requests. Therefore below my answer to the question
The getJSON structure is as follows (found on http://api.jqueri.com):
$(selector).getJSON(url,data,success(data,status,xhr))
most people implement that using
$.getJSON(url, datatosend, function(data){
//do something with the data
});
where they use the url var to provide a link to the JSON data, the datatosend as a place to add the "?callback=?" and other variables that have to be send to get the correct JSON data returned, and the success funcion as a function for processing the data.
You can however add the status and xhr variables in your success function. The status variable contains one of the following strings : "success", "notmodified", "error", "timeout", or "parsererror", and the xhr variable contains the returned XMLHttpRequest object
(found on w3schools)
$.getJSON(url, datatosend, function(data, status, xhr){
if (status == "success"){
//do something with the data
}else if (status == "timeout"){
alert("Something is wrong with the connection");
}else if (status == "error" || status == "parsererror" ){
alert("An error occured");
}else{
alert("datatosend did not change");
}
});
This way it is easy to keep track of timeouts and errors without having to implement a custom timeout tracker that is started once a request is done.
Hope this helps someone still looking for an answer to this question.

Unable to handle scenario: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access

I have a form on a webpage which I'm using to capture data and post to a Google Form. The code I've used I saw on this answer. Now, as expected, I'm receiving an error like the following:
XMLHttpRequest cannot load
https://docs.google.com/forms/d/.../formResponse.
No 'Access-Control-Allow-Origin' header is present on the requested
resource. Origin 'null' is therefore not allowed access.
My script making the request is as follows:
function postToGoogle() {
$.ajax({
url: "https://docs.google.com/forms/d/.../formResponse",
data: {"entry.1691469052": "test message"},
type: "POST",
dataType: "xml",
success: function() {
alert("Success");
},
error: function() {
alert("Error");
}
});
}
$(document).ready(function(){
$('#form').submit(function() {
postToGoogle();
return false;
});
});
Now even though I get the error, my data still persists to the form which is the outcome I want.
The issue I'm facing is that in the event that data is passed, I want to display a message to the user saying the data was received. What I'm trying to do is either:
fix the error through using CORS or similar (methods I'm not familiar with and can't find an answer for on SO)
somehow check within my 'error' function that the only issue is the No 'Access-Control-Allow-Origin' one and then produce a 'success' message in that scenario. If there are other issues I'll just throw an 'error' message back to the user
So far I've not been able to find something that works. Any thoughts?

See the $.ajax doc:
error
Type: Function( jqXHR jqXHR, String textStatus, String errorThrown )
A function to be called if the request fails. The function receives three arguments: The jqXHR (in jQuery 1.4.x, XMLHttpRequest)
object, a string describing the type of error that occurred and an
optional exception object, if one occurred. Possible values for the
second argument (besides null) are "timeout", "error", "abort", and
"parsererror". When an HTTP error occurs, errorThrown receives the
textual portion of the HTTP status, such as "Not Found" or "Internal
Server Error."
So you can write something like:
error: function( jqXHR, textStatus, errorThrown ) {
if( errorThrown.indexOf("Access-Control-Allow-Origin") > 0 ) {
// success...
}
The error text can also be inside jqXHR.responseText.

JQuery ajax query fails very silently

I have read similar questions with similar problems but every advice I read seems to be inefficient for me. Here is the ajax call (I am using Jquery 1.9.1):
$( document ).ajaxError(function() {
alert( "AJAX ERROR" );
});
$.post( "/lists/complete", { itemID:id }, function(answer) {
alert("SUCCESS");
}, "text" ).fail( function() {
alert("ERROR");
}).always( function() {
alert("DONE");
});
On the server side the request is received as expected. If I monitor the server response on the client side (using Firebug), I can see that the server sends the 200 response along with the correct data in the body. However, no alert is never triggered !
What can I do to understand the issue ? I must add that I have very little experience with JS and with Jquery...

I'm also not a fan of jquery post. I prefer using $.ajax. However it is recommended to chain done, fail and always.
$.ajax({
url: ' yoururl ',
type: 'POST',
// dataType: 'default: Intelligent Guess (Other values: xml, json, script, or html)',
data: {param1: 'value1'},
})
.done(function() {
console.log("success");
})
.fail(function() {
console.log("error");
})
.always(function() {
console.log("complete");
});
http://api.jquery.com/jQuery.ajax/
Deprecation Notice: The jqXHR.success(), jqXHR.error(), and
jqXHR.complete() callbacks are deprecated as of jQuery 1.8. To prepare
your code for their eventual removal, use jqXHR.done(), jqXHR.fail(),
and jqXHR.always() instead.

I v never been a fan of the $.post i rather use the full ajax call :
$.ajax({
type: 'POST',
url: '/lists/complete',
data: data,
success: function(data){
alert("SUCCESS");
},
error: function(xhr, type, exception) {
// if ajax fails display error alert
alert("ajax error response type "+type);
}
});
Give this a shot and let me know if the alerts go off.
If this doesn't work out, open up the console (firebug...) and go to the network tab, clear it and send your request.
Click on the request and check the headers and response if they are normal.

$.post is not working (anywhere)! Why?

My calls to $.post are not working all over my code. I'm not sending the request to other domains and, actually, I'm doing everything localhosted. My localhost alias was automatically defined by the Mac OS X 10.8 as ramon.local and I'm requesting from http://ramon.local/linkebuy_0.7/resourceX to http://ramon.local/linkebuy_0.7/resourceY. There are no errors on Chrome's console.
The server side doesn't receive the request and I can check it by accessing directly from the browser (typing the URL).
It's not just one call that is not working, none of them are. They were all working days ago and I'm suspicious that I accidentally changed something on my local settings. What could it be?
Here's an example of what I'm facing:
$.post(
<<CORRECT URL INSIDE THE DOMAIN>>,
{},
function(response) {
console.log('THIS SHOULD BE PRINTED ON CONSOLE');
alert('THIS SHOULD BE POPPED UP');
}
);
I don't get the alert, neither the console message while running the code above. So I tried the following:
$.support.cors = true;
$.ajax({
url: "http://ramon.local/linkebuy_0.7",
dataType: "json",
type: "GET",
crossDomain: true,
success: function (data) {
console.log(data);
},
error: function (xhr, status, error) {
alert(error + " - " + status);
}
});
I just came with $.support.cors = true; and crossDomain: true to check if it was a cross domain issue. So I was alerted No Transport - error same way as before.
What can I do to solve that?
Thanks in advance.

Try this and see if you are getting any alert:
// Assign handlers immediately after making the request,
// and remember the jqxhr object for this request
var jqxhr = $.post("your url", function() {
alert("success");
}).success(function() {
alert("second success");
}).error(function() {
alert("error");
}).complete(function() {
alert("complete");
});
// perform other work here ...
// Set another completion function for the request above
jqxhr.complete(function() {
alert("second complete");
});​

Well, I solved the problem in a very strange way.
I deleted the JQuery file and downloaded it again, replacing the old one. Happens it worked out.
So, if you're:
Making AJAX requests that are not cross-domain;
Using JQuery for it (e.g. $.post, $.get, etc);
Getting No Transport AJAX error
Then re-download and replace you're JQuery source.
Else, if you're making cross-domain requests (not this case), then look for JSONP and try to set $.support.cors = true; at the beginning of you're code.
Thanks everyone for the comments and answers.

Error notification not working

My problem happens to be the error, I am attempting to produce an error, in this case the error being hiding the loading symbol and showing a refresh button in order for the user to reload the page to see if the data loads this time.
$(document).ready(function () {
$('#busy').show();
$(document).bind('deviceready', function () {
var today = $('#todaysong');
$.ajax({
url: 'my url',
dataType: 'jsonp',
jsonp: 'jsoncallback',
timeout: 5000,
success: function (data, status) {
$.each(data, function (i, item) {
var song = '<name>' + item.name + '</name>' + '<artist>' + item.artist + '<br></artist>';
$('#busy').hide();
today.append(song);
});
},
error: function (error) {
$('#busy').fadeOut();
$('#reload').fadeIn();
}
});
});
});
This is my code, could someone advise on what I am doing wrong, I've tried a few things and cannot seem to get it to work, also would I make it so said button was able to refresh this individual piece of code?
Thanks a lot.

In order to debug your code:
Are you generating an error on your own? Is it really an error? Track your request via Firebug or ...
Be sure about running the error function. Again try Firebug or such things to set break points.
Check the JavaScript console for being sure there is no any of damn JavaScript error. And again Firebug error console.

Without seeing other details it is difficult to suggest.
Still I'm trying.. Check the IDs of the elements you have mentioned is same as they are in HTML. Check in HTML that one id is not assigned to more than one element.
In the AJAX code remove jsonp: 'jsoncallback', for a while and test if it is working.

error(jqXHR, textStatus, errorThrown)
A function to be called if the request fails. The function receives
three arguments: The jqXHR (in jQuery 1.4.x, XMLHttpRequest) object, a
string describing the type of error that occurred and an optional
exception object, if one occurred. Possible values for the second
argument (besides null) are "timeout", "error", "abort", and
"parsererror". When an HTTP error occurs, errorThrown receives the
textual portion of the HTTP status, such as "Not Found" or "Internal
Server Error." As of jQuery 1.5, the error setting can accept an array
of functions. Each function will be called in turn. Note: This handler
is not called for cross-domain script and JSONP requests. This is an
Ajax Event.
Where the important part in this case is;
Note: This handler is not called for cross-domain script and JSONP
requests.
Quote from the API documentation of jQuery.ajax.
You should instead be using jsonpCallback.