Develop Reference

Error or fail not being reached when Ajax fails to fetch JSON

I am working on below Ajax code in JavaScript, I am trying to pop up a dialog box when the URL could not load the JSON properly the reason may be either expired token or incorrect token, in any case, I am expecting the code to hit the error or fail but it's not happening. When the URL could load the JSON successfully, success and complete blocks are being hit as expected but nothing is being hit when URL fails. I have tried to use async: false and tried to check with a boolean variable weHaveSuccess but console.log(weHaveSuccess); which is in the last line of the code is getting executing even before success/error is being executed and it seems to me like its still loading asynchronously. I would like to know why error block is not being hit when the JSON load from URL is getting failed.
My code
function checkUser(myURL, newAccessToken, weHaveSuccess) {
$.ajax({
type: "GET",
dataType: "jsonp",
async: false,
url: myURL + newAccessToken,
error: function (XMLHttpRequest, textStatus, errorThrown) {
console.log("Status: " + textStatus);
console.log("Error: " + errorThrown);
},
success: function (data) {
console.log("Hello 2 " + JSON.stringify(data));
weHaveSuccess = true;
console.log('Message from Success ' + weHaveSuccess);
},
complete: function () {
console.log('Message from Complete ' + weHaveSuccess);
}
}).done(function (data) {
alert("Success");
console.log(data);
}).fail(function (data) {
console.log(data);
alert("Failed");
}).always(function () {
alert("In Always");
});
console.log(weHaveSuccess);
}
Thanks in advance!

AJAX requests are asynchronous. It takes time for a remote request to be made and responded to. You will have to write your post-response code within the success function or call another function from there, not within the same scope as where the call is initiated.
I am taking a bit of a guess here about what your server returns on failure. An AJAX request success means simply that a 200 OK response was received, without any consideration of the contents of the data. If an error is simply a change in the data you will need do one of the following to show an error:
Have the server set a status code header on failure, perhaps 400 Bad Request.
In the success function look within your data for whatever error response you are expecting and trigger the alert() there.

First of all the console.log(weHaveSuccess); fires first, because the $.ajax() is asynchronous while console.log is not so ajax will be triggered and return the promise when finishes, but the browser will continue with the script.
In the jQuery ajax docs says:
Cross-domain requests and dataType: "jsonp" requests do not support
synchronous operation.
It's hard to debug without seeing the response, maybe you can add some info from the network or a URL?

How about if you try the following:
Add the jsonp setting to your $.ajax() function for the callback that will handle the response and console.log there:
function myCallback(data) {
console.log(data);
}
$.ajax({
type: "GET",
dataType: "jsonp",
jsonp: myCallback,
...

Jquery ajax response not calling Success method

I am pretty much new to ajax and working on jquery ajax request. Ajax callback is not calling success method. Interaction is between cross-site domains.
My AJAX request looks like
$.ajax({
timeout: 20000,
url: 'test.com',
crossDomain: true,
dataType: 'jsonp',
success: function (data) {
console.log('callback success');
this._cache = data;
localStorage.token = data.access_token;
} });
There are no errors in this call.
This ajax request is not calling success function.Request is returning json data. it's just success method is not getting called.
This ajax request is not calling success function.
Get request is getting fired successfully. I can even trace the response in fiddler with 200 http response.For some reason success method is not getting called.

it's returning json object, which I've traced in fiddler
You're telling jQuery to expect a JSONP response, so it is trying to execute the JSON document as if it were a JavaScript script (because that is what JSONP is). This fails because it is not JSONP.
Either return JSONP instead of JSON or (assuming the server returns the correct Content-Type) remove dataType: 'jsonp',.

ok... I came here with the same problem... and when I read that specifying datatype:jsonp never calls success as a callback per #mondjunge from a comment above, it started me thinking about some behavior I saw earlier from my code and that maybe datatype:json might have the same behavior for what ever reason here too.
So after reading this page I took out my datatype declaration from my ajax request and my servlet returned the proper data payload, returned a 200, and jquery called the success function finally and modified my DOM.
All those steps happened except the last one until I removed my datatype from my ajax call. NOT what I was expecting!
Hopefully someone else can shed some light on why this happens... for now at least the few that don't lose their minds to this issue that find this post can do this in the mean time.

Check if your ajax is executed
Check it's status. If response code is != 200, than you should add error method also, for error handling.
Try this:
$.ajax({
timeout: 20000,
url: 'test.com',
method: 'GET',
crossDomain: true,
dataType: 'jsonp',
success: function (data) {
console.log('callback success');
this._cache = data;
localStorage.token = data.access_token;
},
error: function(xhr, error){
console.debug(xhr); console.debug(error);
},
});

How to cancel an ajax request or third party js request when no response after x time w/ abort()

Curious what are some of your solutions, elegantly, that deal with block js calls / ajax calls that take too long reaching out to third party sites for data/info.
Lately, I've been contending with some scripts/ajax requests in which the server is either down or not responding and literally blocks my page. They are suppose to be async.
So, I want to abort the call after x time.
var request = $.ajax({
type: 'POST',
url: 'someurl',
success: function(result){}
});
then use: request.abort() if it takes too long.
But I am thinking I can use a deferred/promise here, with a timeout ability and call abort if my promise doesn't come back in say 1000ms.
Your thoughts?
My bad for not referring to the timeout attr of the ajax request. I didn't want to wrap the abort() in a setTimeout, but having the jQuery ajax api w/ timeout is what I need. I should have seen this. thanks all.

Check the timeout option: http://api.jquery.com/jQuery.ajax/
var request = $.ajax({
type: 'POST',
url: 'someurl',
timeout: 2000,
success: function(result){},
error: function(xhr, status, message) {
if(status == "timeout") {
alert("Request time out");
}
}
});

One way can be using setTimeout
var abort_req = setTimeout(function () {
request.abort();
}, 3000);
//^ time in ms

Possible duplicate of jQuery $.ajax timeout setting. JQuery AJAX has an optional timeout option that can be passed by milliseconds. You can process logic when the AJAX request timed out by passing a callback function to the error option like so:
error: function(x, t, m){
//process error here
}

jQuery $.ajax call works in Chrome, but not any other browser

The following call works perfectly in Chrome, but fails in every other browser.
function getInfo(r,c,f){
return $.parseJSON($.ajax({
url: baseURL + 'somethingAPI/getInfo',
data: {
"data_r": r,
"data_c": c,
"data_f": f
},
//success: function(data){},
dataType: "json",
async: FALSE
}).response);
}
Yes, I'm using a synchronous ajax call and I believe it is necessary as I don't want any of the other JS to run without this executing and returning data. Although, I'm not entirely sure if something else should be happening with the success callback.
Anyway, in Chrome I get the response object (JSON) and can access the data within just fine.
Does anyone know what I'm doing wrong?

Regarding your point about not knowing how to avoid async: false, is this something like what you're looking to accomplish?
function getInfo(r, c, f, callback) {
$.ajax({
url: baseURL + 'somethingAPI/getInfo',
data: {
"data_r": r,
"data_c": c,
"data_f": f
},
dataType: "json",
success: callback,
});
}
getInfo('foo', 'bar', 'baz', function(response) {
console.log(response);
});

Rather than parsingJson on the ajax query, here's the syntax I use to conquer these challenges
$.ajax({
url: "pagegoeshere.php",
timeout: 30000,
type: "POST",
data: 'data1='+data1+'&data2='+data2,
dataType: 'json',
error: function(XMLHttpRequest, textStatus, errorThrown) {
alert("An error has occurred making the request: " + errorThrown)
},
success: function(returnjson){
var returnstuff = returnjson.returnstuff;
//Do next Javascript step here
}
});
You can run ensuing javascript/jquery in the success and "stack" events together on success of your Ajax call. That way, if it works, it proceeds. Otherwise, the error handling can occur in the provided error section in a manner that you define. I generally fire my ajax calls on a click handler, but it's certainly doable to run it in a function as you have chosen. Be sure to check your return JSON (could be mailed from your processing page, for example) to make sure it's valid JSON. Jsonlint is your friend!
I've had chrome effectively parse bad HTML and JSON while the other browsers don't on several occasions. I'd suspect it's something along those lines that's specifically causing your issues.

A quick question on data returned by jquery.ajax() call (EDITED)

EDIT: The original problem was due a stupid syntax mistake somewhere else, whicj I fixed. I have a new problem though, as described below
I have the following jquery.ajax call:
$.ajax({
type: 'GET',
url: servicesUrl + "/" + ID + "/tasks",
dataType: "xml",
success : createTaskListTable
});
The createTaskListTable function is defined as
function createTaskListTable(taskListXml) {
$(taskListXml).find("Task").each(function(){
alert("Found task")
}); // each task
}
Problem is: this doesn't work, I get an error saying taskListXml is not defined. JQuery documentation states that the success functions gets passed three arguments, the first of which is the data.
How can I pass the data returned by .ajax() to my function with a variable name of my own choosing.
My problem now is that I'm getting the XML from a previous ajax call! How is this even possible? That previous function is defined as function convertServiceXmlDataToTable(xml), so they don't use the same variable name.
Utterly confused. Is this some caching issue? If so, how can I clear the browser cache to get rid of the earlier XML?
Thanks!

See my comment. If you're using IE, GET AJAX requests are cached. jQuery can solve this for you by adding a random querystring variable to the request. Simply change your AJAX call to this:
$.ajax({
type: 'GET',
url: servicesUrl + "/" + ID + "/tasks",
cache: false,
dataType: "xml",
success : createTaskListTable
});
That will add the random querystring automatically, thus preventing the browser from caching the request.

Try defining your callback inline like this:
success: function createTaskListTable(data, textStatus, xhr) {
console.dir(data, textStatus, xhr);
}
If data is indeed being returned as null, you might get some insight from the other fields, especially xhr.
Note that error callbacks get called with (xhr, textStatus, errorThrown).