Develop Reference

How to stop AJAX making multiple calls?

I'm using the jquery countdown timer plugin (http://keith-wood.name/countdown.html) to display the time. I'm calling a function to add more time on callback event 'onTick'. When the time countdowns to 00:00:00, the function will make an ajax call to add extra time. It's working fine but every time the timer equals 00, ajax is making multiple calls (>15). How can I make it to send just one call? I tried doing async: false but still it's making multiple calls. Thank you.
$(this).countdown({ until: time, format: 'HMS', onTick: addExtraTime });
function addExtraTime() {
if ($.countdown.periodsToSeconds(periods) === 00) {
var postValue = { ID: id }
if (!ajaxLoading) {
ajaxLoading = true;
$.ajax({
url: "#Url.Action("AddExtraTime", "Home")",
type: 'post',
dataType: 'json',
contentType: "application/json",
data: JSON.stringify(postValue),
success: function() {
// show success
},
error: function(data) {
// show error
}
});
ajaxLoading = false;
}
}
}

You have a variable, ajaxLoading, that you use to determine if an Ajax request is in flight but you set it to false immediately after calling $.ajax() instead of when you get a response. Set it to false inside your success and error handlers instead.

You're setting ajaxLoading = false; even when the ajax request is still being done, set it to false after the request is completed
if (!ajaxLoading) {
ajaxLoading = true;
$.ajax({
url: "#Url.Action("AddExtraTime", "Home")",
type: 'post',
dataType: 'json',
contentType: "application/json",
data: JSON.stringify(postValue),
success: function() {
// show success
},
error: function(data) {
// show error
}
complete: function(){
ajaxLoading = false;
}
});
//ajaxLoading = false;
}

Ajax - All request are Done/Completed

I have a difficulty to know when all Ajax requests are completed because I need this information to call another function.
Difficulty are to know when my 4/5 function with requests are completed. I use native function of ajax and none is working for me.
I used Chrome, and async requests.
Someone Helps me
I use this(not work):
$(document).ajaxStop(function() {
alert("Completed");
});
and this (not Work):
$(document).ajaxComplete(function() { alert("Completed"); });
Both ways I try use in another function thal calls all requests:
Example:
function Init()
{ Search("123"); Search2("1234"); Search3("12345");
... }
Extract one (of 5 requests,others are very similar ) of my request:
function Search(user) {
$.ajax({
url: 'www.example.com/' + user,
type: 'GET',
async: true,
dataType: 'JSONP',
success: function(response, textStatus, jqXHR) {
try {
if (response != null) {
alert("Have Data");
} else {
alert("are empty");
}
} catch (err) {
alert("error");
}
},
error: function() {
alert("error");
}
}); }

have you tried putting it in a done function? something like...
$.ajax({
url: 'www.example.com/' + user,
type: 'GET',
async: true,
dataType: 'JSONP'
}).done(function (data) {
code to execute when request is finished;
}).fail(function () {
code to do in event of failure
});
bouncing off what Michael Seltenreich said, his solution, if i understand where you guys are going with this...might look something like:
var count = 0;
function checkCount(){
if(count == 5 ){
//do this, or fire some other function
}
}
#request one
$.ajax({
url: 'www.example.com/' + user,
type: 'GET',
async: true,
dataType: 'JSONP',
}).done( function(data){
count += 1
checkCount()
})
#request two
$.ajax({
url: 'www.example.com/' + user,
type: 'GET',
async: true,
dataType: 'JSONP',
}).done( function(data){
count += 1
checkCount()
})
and do it with your five requests. If that works out for you please make sure to mark his question as the answer;)

You can create a custom trigger
$(document).trigger('ajaxDone')
and call it when ever you finished your ajax requests.
Then you can listen for it
$(document).on('ajaxDone', function () {
//Do something
})
If you want to keep track of multiple ajax calls you can set a function that counts how many "done" values were passed to it, and once all are finished, you can fire the event.
Place the call for this function in each of the 'success' and 'error' events of the ajax calls.
Update:
You can create a function like so
var completedRequests= 0
function countAjax() {
completedRequests+=1
if(completedRequests==whatEverNumberOfRequestsYouNeed) {
$(document).trigger('ajaxDone');
}
}
Call this function on every success and error events.
Then, ajaxDone event will be triggered only after a certain number of requests.
If you wanna track specific ajax requests you can add a variable to countAjax that checks which ajax completed.

JQuery ajax() done / fail callbacks not returning upon status 200

I'm trying to post a form data using JQuery to a remote servlet.
I can see that the server receives the data and also returns status code 200 and a response string of "{result: 'success'}"
But the ajax call doesn't return with the done or fail functions (if I add an always function than I can see that it is being called)
Here's a code snippet of the client side:
`
var dataParams = 'email='+email+'&password='+password;
var url = 'http://127.0.0.1:8888/signup';
var jxhr = $.ajax({
type : "POST",
url : url,
data : dataParams,// serializes the form's elements.
dataType: "json",
done: function() {
console.log("done!");
hideSignUp();
showThankYou(); },
fail: function() {
console.log("fail!");
}
});
`
Seems like I'm missing out on something, but can't seem to find what.
Note that I'm using JQuery 1.8.3 so success is deprecated.
Any thoughts?

Try:
var url = "http://127.0.0.1:8888/signup";
var jxhr = $.ajax({
type : "POST",
url : url,
data : dataParams,// serializes the form's elements.
dataType: "json"
}).done(function() {
console.log("done!");
hideSignUp();
showThankYou();
}).fail(function(jqXHR, textStatus) {
console.log(textStatus);
});

Try chaining your callbacks, rather than setting them as object fields:
$.ajax({
type : "POST",
url : url,
data : dataParams,// serializes the form's elements.
dataType: "json"
}).done(function (xhrResponse) {
console.log("done!");
hideSignUp();
showThankYou();
}).fail(function (xhrResponse, textStatus) {
console.log(textStatus);
}).always( function () {
console.log("I'm done with this.");
});
By chaining your callbacks, you guarantee execution of at least one (complete).

JQuery Ajax call, return value problem

function getMore(from){
var initData = "&start-index=";
initData += from;
$.ajax({
type:"POST",
url: '', //removed the URL
data: initData,
dataType: 'json',
success: function(result) {
return result;
},
error: function(errorThrown) {
}
});
return result;
}
Its a google base query; I have another function that makes the initial server call and gets the first 250 items. I then have a running counter and as long as the results = 250 it calls the server again, but starting at "start-index=" of the current amount of items pulled off. This part all works correctly and with firebug I can also see that the server response is proper JSON.
The trouble I'm having is trying to return the JSON from this function to the function that called it. I do not want to call the original function again because it will clear the arrays of data already pulled from the server. Each time it returns to the parent function it's null.
Does anyone know how i can go about returning the data using "return"?

function FuncionCallGetMore(){
//...
getMore('x-value', FuncionGetReturn);
//...
}
function FuncionGetReturn(error, value){
if (!error) {
// work value
}
}
function getMore(from, fn){
var initData = "&start-index=" + from;
$.ajax({
type:"POST",
url: '', //removed the URL
data: initData,
dataType: 'json',
success: function(result) {
fn(false, result);
},
error: function(errorThrown) {
fn(true);
}
});
return;
}

The only way that you can do what you're describing is to make the AJAX call synchronous, which you don't want to do since it will lock the UI thread while the request is being made, and the browser may will to freeze. No one likes freezing.
What you want to do is use callbacks. Post the code of the other functions involved so I can get a better idea of what is going on. But basically, what you want to do is to create an asynchronous loop.
function listBuilder() {
var onError = function(response) {
// ...
};
var onSuccess = function(response) {
// Handle the items returned here
// There are more items to be had, get them and repeat
if ( response.length == 250 ) {
getMore(onSuccess, onError, 250);
}
};
getInitialSet(onSuccess, onError);
}
function getMore(onSuccess, onError, from) {
$.ajax({
type:"POST",
url: '', //removed the URL
data: "&start-index=" + from,
dataType: 'json',
success: onSuccess,
error: onError
});
}

How to callback a function on 404 in JSON ajax request with jQuery?

I want to make an Ajax request with response in JSON. So I made this Ajax request:
$.ajax({
url: 'http://my_url',
dataType: "json",
success: function(data){
alert('success');
},
error: function(data){
alert('error');
},
complete: function(data) {
alert('complete')
}})
This code works good but when my url send me a HTTP code 404, no callbacks are used, even the complete callback.
After research, it's because my dataType is 'json' so 404 return is HTML and the JSON parsing failed. So no callback.
Have you a solution to call a callback function when a 404 is raised ?
EDIT: complete callback don't call is return is 404. If you want an URL wit 404 you can call : http://twitter.com/status/user_timeline/jksqdlmjmsd.json?count=3&callback=jsonp1269278524295&_=1269278536697 it's with this URL I have my problem.

$.ajax({
url: 'http://twitter.com/status/user_timeline/jksqdlmjmsd.json?count=3&callback=jsonp1269278524295&_=1269278536697',
dataType: "json",
success: function(data) {
alert('success');
},
error: function(data) {
alert('error');
},
complete: function(xhr, data) {
if (xhr.status != 0)
alert('success');
else
alert('fail');
}
})

With your configuration jQuery uses jsonp to transport the data. This works by dynamically inserting a script element and setting the URL to the specified value. The data returned by the server is then evaluated as JavaScript - usually calling the provided callback. If the server returns a 404, the contents is obviously no JavaScript and the callback is never called. Some browsers support error handlers on the script tag, which are called in these situations. Unfortunately IE doens't support this. The best way to detect an error is to rely on a timeout.
In your case you should specify an additional timeout option, which causes the error handler to be called if the callback wasn't called in time (which would be the case for a 404 response).
$.ajax({
url: 'http://my_url',
timeout: 2000, // 2 seconds timeout
dataType: "json",
success: function(data){
alert('success');
},
error: function(data){
alert('error');
},
complete: function(data) {
alert('complete')
}
});

Use the statusCode-Option
$.ajax({
url: 'http://my_url',
dataType: "json",
statusCode: {
404: function() {
alert("I could not find the information you requested.");
}
},
success: function(data) {
alert('success');
},
error: function(data) {
alert('error');
},
complete: function(data) {
alert('complete');
}
})

If you want to handle errors when accessing the Twitter API with Javascript and jsonp you need to include the parameter suppress_response_codes in your request. This makes all responses from the Twitter API respond with a 200 OK response and include a error. Then you need to check if the response includes the error parameter or not.
$.ajax({
url: "https://api.twitter.com/1/users/show.json",
dataType: 'jsonp',
jsonp: "callback",
data: {
screen_name: "simongate1337",
suppress_response_codes: true // <- Important part
},
success: function(data) {
if(data.error) {
console.log("ERROR: "+data.error);
} else {
console.log("Success, got user " + data.screen_name);
}
}
});

Do not you think that the problem is not with the dataType but with cross-domain requests that you are not allowed to make?
The code below works as expected when you request data from the same domain and does not when you are making cross-domain requests:
function handle404(xhr){
alert('404 not found');
}
function handleError(xhr, status, exc) {
// 0 for cross-domain requests in FF and security exception in IE
alert(xhr.status);
switch (xhr.status) {
case 404:
handle404(xhr);
break;
}
}
function dumbRequest() {
var url = 'http://twitter.com/status/user_timeline/jksqdlmjmsd.json?count=3&callback=jsonp1269278524295&_=1269278536697';
url = 'http://twitter.com/';
url = '/mydata.json';
// url = 'mydata.json';
$.ajax(
{url: url,
dataType: 'json',
error: handleError}
);
}

Is it simply because the dataType is set to "json"? If so, try changing it to text and evaluate the JSON yourself:
$.ajax({
url: 'http://twitter.com/status/user_timeline/jksqdlmjmsd.json?count=3&callback=jsonp1269278524295&_=1269278536697',
dataType: 'text',
success: function(data, status, xmlHttp) {
try {
data = eval('(' + data + ')');
alert('success');
} catch (e) {
alert('json parse error');
}
},
error: function(xmlHttp, status, error) {
alert('error');
},
complete: function(xmlHttp, status) {
alert('complete');
}
});

Are you aware that even though the HTTP status is 404, the actual body is valid JSON? For instance, this link has the following JSON:
jsonp1269278524295({"request":"/status/user_timeline/jksqdlmjmsd.json?count=3&callback=jsonp1269278524295&_=1269278536697","error":"Not found"})
As such, you should check if your data has the error property within your normal callback function.
UPDATE: apparently, even though the actual content of the page is valid JSON, the browser (I checked in Firefox) is not executing it, most likely because it is a 404. Because jQuery has to add a script element (because of the cross-domain issue), its JSONP wrapper is never called, and as a consequence, neither are your callbacks.
So, in short, I don't think there is a way to deal with this without manually adding that script element and checking if your pre-defined callback function has been called afterwards.

Just faced the same issue, and saw another question mentioned that jQuery-JSONP (jQuery Plugin) supports catching 404 errors or as they describe: "error recovery in case of network failure or ill-formed JSON responses"
And it works perfect :)
Here is my (simplified) code for fetching details about a YouTube video via JSONP:
$.jsonp(
{
url: "https://gdata.youtube.com/feeds/api/videos/ee925OTFBCA",
callbackParameter: "callback",
data:
{
alt: "jsonc-in-script",
v: "2"
},
success: function(json, textStatus)
{
console.log("WEEEEEEEE!");
},
error: function(xOptions, textStatus)
{
console.error(arguments);
}
});

Here's how I deal with this. I check the returned data for errors before trying to use it. What is shown below is just a sample that you could extend to more closely match your requirements. This also considers session time outs and other scenarios...
My initial call:
$.ajax({ type: 'POST',
url: '../doSomething',
data: 'my data',
success: function(data) {
if (HasErrors(data)) return;
var info = eval('(' + data + ')');
// do what you want with the info object
},
error: function(xmlHttpRequest) {
ReportFailure(xmlHttpRequest);
}
});
And the two helper functions:
function HasErrors(data) {
if (data.search(/login\.aspx/i) != -1) {
// timed out and being redirected to login page!
top.location.href = '../login.aspx';
return true;
}
if (data.search(/Internal Server Error/) != -1) {
ShowStatusFailed('Server Error.');
return true;
}
if (data.search(/Error.aspx/) != -1) {
// being redirected to site error reporting page...
ShowStatusFailed('Server Error. Please try again.');
return true;
}
return false;
}
and
function ReportFailure(msg) {
var text;
if (typeof msg == 'string') {
text = msg;
}
else if (typeof msg.statusText == 'string') {
if (msg.status == 200) {
text = msg.responseText;
}
else {
text = '(' + msg.status + ') ' + msg.statusText + ': ';
// use the Title from the error response if possible
var matches = msg.responseText.match(/\<title\>(.*?)\<\/title\>/i);
if (matches != null)
{ text = text + matches[1]; }
else
{ text = text + msg.responseText; }
}
}
// do something in your page to show the "text" error message
$('#statusDisplay')
.html('<span class="ui-icon ui-icon-alert"></span>' + text)
.addClass('StatusError');
}

Following solution is working fine for me :)
$.ajax({
url: 'http://my_url',
dataType: "json",
success: function(data){
alert('success');
},
error: function(data){
alert('error');
},complete: function(xhr, data) {
if(data==="parsererror"){
alert('404');
}
}
});