Develop Reference

Ajax request failing?

I am trying to retrieve json data from an api.
It keeps failing, but when I look in the Net tab of Firebug I can see that the GET request executed and returned the correct data. Am I doing something wrong or does anyone have tips on how to debug this?
Edit: Have changed to dataType json and error status code is 0
Thanks
$.ajax({
url: 'http://localhost:55894/api/Test/All',
data: {
format: 'json'
},
error: function () {
alert('Error');
},
dataType: 'jsonp',
success: function (data) {
alert('Ok');
},
type: 'GET'
});

From the info you provided the reason it is failing is because you dont have a cross domain access policy setup. Because you are using different ports to host the website and the API you are running into this issue. You can either setup a crossdomain.xml with the proper security settings or you can move both the API and the webserver to the same port.
Have a look at this for more info: http://en.wikipedia.org/wiki/Same-origin_policy

u can try this way:
$.ajax({
type: 'GET',
url: 'url api here',
beforeSend: function() {
},
success: function(data) {
},
error: function(xhr) { // if error occured
},
complete: function() {
},
dataType: 'json'
});

JSON and JSONP are different. If you are using JSONP, the server side must be prepared to support it. Doesn't look like you are using JSONP.
So just change dataType to 'json', as you are "trying to retrieve json data".

Real time refreshing chat using jQuery $.Ajax for both computers

I found a script for real chat using $.ajax jQuery, but it refereshes only my massages. For example:
I write to You: Hello, this message refresh for me.
You write to me: Hey, to see your message I must refresh a site by clicking F5, but You do not have to click F5. Something wrong!
My $.ajax code:
$(document).ready(function() {
$("#lupnijto").click(function (e) {
$("#lupnijto").hide();
$("#LoadingImage").show();
var zeszyt_value = 'zeszyt='+ $("#contentText").val(); //build a post data structure
jQuery.ajax ({
type: "POST",
url: "response.php",
dataType: "text",
data: zeszyt_value,
cache: false,
success: function(response) {
$("#responds").prepend(response);
$("#contentText").val('');
$('#contentText').focus();
$("#lupnijto").show();
$("#LoadingImage").hide();
},
error:function (xhr, ajaxOptions, thrownError) {
$("#lupnijto").show();
$("#LoadingImage").hide();
alert(thrownError);
}
});
});
});
What am I doing wrong? Why data only refreshes for me? How the chat works? Am I doing it correct? I accept answers. Thanks.

For such real time applications, you need to use WebSockets: On MDN
,you can also check on some WebSockets API Socketio for Node.js
I do advice those, but also you can use AJAX (not recommended).

You can use Socket.IO. For non-WebSockets browsers you can use Engine.IO.

Catch / Handle 502 Bad Gateway Error

I have to update a large collection so I am calling in a loop an web api. I use jQuery.ajax()
Something like this:
$.ajax({
type: 'GET',
url: 'http://www.somesite.com/API/API.php',
jsonpCallback: 'API_SC4',
contentType: "application/json",
dataType: 'jsonp',
data:'action=update&page='+collection[currentIndex].name+'&callback=API_SC4',
async:false,
success: function(data) {
//use data for update of collection[currentIndex]
UpdateNext(currentIndex+1);
},
error: function(e) {
//interpret error
UpdateNext(currentIndex+1);
}
});
The problem is the collection is quite large and sometimes I get a 502 Bad Gateway error and the ajax error handler is not called.
I even tried $( document ).ajaxError() but i'm doing a cross-domain jsonp call , and it seems .ajaxError() does not get called in that situation.
Is there any way to handle that error? Something at window level?
I can see the error in the Chrome development console , and I was thinking there might be a way.
Thanks

Yes, there is: statusCode. See the jQuery documentation on AJAX for details.
Simple example:
$.ajax({
statusCode: {
502: function () {
alert('Fail!');
}
}
});

jQuery AJAX not receiving JSON from http request

I ame using html with some jQuery to try out some JSON requests. I did a bit of research and tried making something small just to test it out. but when i run the script in my browser(Google Chrome) i dont get anything besides my html/css stuff. here is the code:
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js">
console.log("Test");
console.log($.get("https://prod.api.pvp.net/api/lol/euw/v1.1/summoner/by-name/kerrie?api_key=[key]"));
</script>
*[key] is my key from the api owners(not to be shared on the internet).
when i check the network tab it says "304, not modified" i dont if this has anything to do wit it.
I'm just starting with websites and JavaScript/jQuery any help would be helpfull.

For better understanding you can call ajax method as below
$.ajax({
url: 'https://prod.api.pvp.net/api/lol/euw/v1.1/summoner/by-name/kerrie?api_key=[key]',
type: 'GET',
dataType: 'JSON',
async: false,
error: function(){},
success: function(resp){
// resp variable will be your JSON responce
}
}
});

How to stop timed out ajax call using JQuery

I have an ajax application, which has code something like this:
$.ajax({
type: "GET",
url: "data.txt",
beforeSend:function(){
},
success:function(response){
just update responsed data;
}
});
this call is made every second and it just updates the latest data from 'data.txt' which is being updated on server using cron job. Now since it's only function is to update latest data each second so I'll be more interested in the latest ajax call ; so how can I terminate old ajax call that has crossed 4 seconds but yet not completed so that I can reduce the server traffic. And any suggestion if using 'data.html' or 'data.php' instead of 'data.txt' would increase the application performance ? And which web server can perform better than Apache for ajax driven application ? I need these help urgently ; Please do help.

You could keep track of when your last successful update time was.
function NowMS() {return parseInt(new Date().getTime())}
dataLastUpdateT = -Infinity;
$.ajax({
type: "GET",
url: "data.txt",
success: function(response){
if (NowMS() > dataLastUpdateT) {
use(response);
dataLastUpdateT = NowMS();
}
}
}

I don't know how you have it setup at the moment but perhaps it would be better to run your next AJAX call after the latest one completed (or returned an error). So it would be something like:
(function updateData() {
$.ajax({
type: 'GET',
url: 'data.txt',
beforeSend: function() {
// Do stuff
},
success: function(response) {
// Handle response
updateData();
}
});
})();
I don't know if there is any performance changes in changing the file type.
Edit: If you do need to just kill the request, you can do so using the technique explained here.

You could try this:
function getData(){
$.ajax({
type: "GET",
url: "data.txt",
timeout:4000,
beforeSend:function(){
},
success:function(response){
},
error:function(){
},
complete:function() {
setTimeout(function(){getData();},1000);
}
});
}
getData();
this way the ajax request timeouts after 4 seconds and retries each second (regardless of success or timeout)
Also have a look at nginx for example, it is fast and uses less memory than apache to handle client connections