jQuery ajax asyncrhonous calling - javascript

I'm trying to make some actions after an ajax call done with jquery.
I have seen that if i use a function like this:
function DownloadData() {
$.ajax({
url: "/api/AlbumsRest",
accepts: "application/json",
cache: false,
success: function () {
/*binding stuff*/
},
error: function (XMLHttpRequest, textStatus, errorThrown) {
alert('Error' + textStatus);
}
});
}
The ajax request it's done in async mode. I don't want to change it because i don't want to freeze the page. But i would like to make some actions (animations, effects etc) after this ajax is completed.
So, my question is, how can i to know if i'm at the end of this request without using the success event
If i call DownloadData function like this:
function DownloadNextData() {
DownloadData();
SlideOutAnimation();
SlideInAnimation();
}
I need to make slides after async request has been made.
Some idea ?

Using jQuery Deferred Objects you should return the result of $.ajax() from DownloadData
function DownloadData() {
return $.ajax({...});
}
and then you can register a function outside of your AJAX handler that'll only get called once the AJAX call has completed:
function DownloadNextData() {
DownloadData().done(function() {
SlideOutAnimation();
SlideInAnimation();
});
}
behold - your animation processing is completely decoupled from your AJAX function :)
To simplify things, .done can also actually take a list of function references:
function DownloadNextData() {
DownloadData().done(SlideOutAnimation, SlideInAnimation);
}
Note that in this case you can't supply your own function arguments - they'll actually get passed the contents of the AJAX data.

function DownloadData() {
return $.ajax({
url: "/api/AlbumsRest",
accepts: "application/json"
});
}
function DownloadNextData() {
SlideOutAnimation();
SlideInAnimation();
}
DownloadData().done(DownloadNextData);

Try $.ajaxcomplete. here is the documentation for it http://api.jquery.com/ajaxComplete/

Related

How to work with JSONP to call back the function?

I am trying to communicate with a server using JSONP call back.
Here is my code
$('.icwsDownloadRecording').click(function(){
var id = $(this).attr('data-recordingid');
$.ajax({
type: 'GET',
url: 'http://example.com/Default2.aspx',
data: {'ID': id},
dataType: 'jsonp',
cache: false,
timeout: 40000,
crossDomain:true,
jsonp: "MyCallbackFunction",
});
});
function MyCallbackFunction(data)
{
//process data further
console.log(data);
if(!data || data.url.length < 5){
return;
}
var $preparingFileModal = $("#preparing-file-modal");
$preparingFileModal.dialog({ modal: true });
$.fileDownload( data.url, {
successCallback: function (url) {
$preparingFileModal.dialog('close');
},
failCallback: function (responseHtml, url) {
$preparingFileModal.dialog('close');
$("#error-modal").dialog({ modal: true });
}
});
return false; //this is critical to stop the click event which will trigger a normal file download!
}
The issue here is that I keep getting this message in the console
ReferenceError: MyCallbackFunction is not defined
I do have this defined as you can see in my code above
The server respond looks like this
MyCallbackFunction("{'URL': 'http:\/\/example.com:8106\/ghjgj3835396265336634646562363030303122226D616C686179656B22535353557DBE0C305645E2DE110AA1D7F8792E96A3'}");
how can I correct this issue?
EDITED
This is my code after Quentin Answer , this is my new code
$(function(){
$('.icwsDownloadRecording').click(function(){
var id = $(this).attr('data-recordingid');
$.ajax({
type: 'GET',
url: 'http://example.com/Default2.aspx',
data: {'ID': id},
dataType: 'jsonp',
timeout: 40000,
success: function(data){
//process data further
console.log(data);
if(!data || data.url.length < 5){
return;
}
var $preparingFileModal = $("#preparing-file-modal");
$preparingFileModal.dialog({ modal: true });
$.fileDownload( data.url, {
successCallback: function (url) {
$preparingFileModal.dialog('close');
},
failCallback: function (responseHtml, url) {
$preparingFileModal.dialog('close');
$("#error-modal").dialog({ modal: true });
}
});
return false; //this is critical to stop the click event which will trigger a normal file download!
}
});
});
});
Unless you have all of that code wrapped in another function, that should work.
Using a hardcoded function name is bad practise though.
Update:
$(function(){
You do have all that code wrapped in another function.
Remove this:
jsonp: "MyCallbackFunction",
Replace it with:
success: MyCallbackFunction
Or you could put an anonymous function expression there instead (as you have done in your edit)
Let jQuery generate a unique function name (which protects you from race conditions) and allow the server to use the callback query string argument to determine what function name to use.
MyCallbackFunction is in the same scope as the ajax call, so it will be available to the function (which can copy it to a suitably named global).
After you fix that, you have an additional problem:
MyCallbackFunction("{'URL':
Your response is JSON encoded in a JavaScript string, but you are trying to treat it as a JavaScript object.
Either:
Fix the server so it doesn't stringify the JSON or
Run the first argument through JSON.parse
crossDomain:true,
Remove that. It doesn't do anything here. (All it does is, when using XHR (which you aren't using) to the same origin (which you aren't targeting), suppress the custom headers that aren't typically allowed on a cross-origin request so that you can perform an HTTP redirect to a different origin).
cache: false,
That's the default for JSONP requests. Including it is pointless.
return false; //this is critical to stop the click event which will trigger a normal file download!
If you want to stop the click event, then you need to return false from the click event handler function (not the Ajax success handler).
You can't wait until the Ajax function has run and got a response before doing that. Ajax is asynchronous.

Restart ajax object with jquery

I have a code like this:
object1 = $.ajax({
..
..
});
In the event of error I want to be able to restart the ajax, for example, if the connection of the user drops I want to be able to call the same ajax again without having to make $.ajax(.....). Is it possible to do something like:
object1.restart();
?
put it in a function:
function callAjax() {
$.ajax({
..
..
});
Then its like callAjax() if theres an error..
That is easy, and jQuery allows you to do that inside an Ajax request. Have a look
$.ajax({
/* full ajax body */
url: 'page.html',
data: 'if-any',
success: function () {
/* show that ajax request has finished */
},
error: function () {
/* restart the ajax request, by re executing the function */
}
});
You can try this:
function ajax_request () {
$.ajax({
/* full ajax body */
url: 'page.html',
data: 'if-any',
success: function () {
/* show that ajax request has finished */
},
error: function () {
ajax_request(); // using this, you can re execute the function
}
});
}
$.when() is a potential candidate here,
for eg.
var object1 = $.ajax({
..
..
});
$.when(object1).fail(object1);

values won't get updated in a function because of a ajax call

I'm writing a javascript function that should change the view of a postcard depending on which case is selected.
My problem is that the old values of the object "m_case" is getting used. If I press the button with class "case-btn" twice I get the right case selected in my postcard view. But I want it to be triggered when I press the button once.
I guess I have to do something like a callback function in the m_case.setCase() function call, but I can't get it working,
$('.case-btn').on('click', function() {
remove_active_state_from_cases();
m_case.setCase($(this).data('case'));
// Changes the view of the postcard
m_postcard.changeBackground(m_case.getPhoto());
m_postcard.changeMessage(m_case.getMessageText());
m_postcard.changeFullName(m_case.getFullName());
m_postcard.changeCountry(m_case.getCountry());
$(this).toggleClass('active');
});
The setCase() function
this.setCase = function(id) {
// Set ID
this.setID(id);
var that = this;
$.ajax({
url: 'get_case_by_id.php',
type: 'get',
dataType: 'json',
data: {id: that.getID() },
success: function(data) {
if(data.success) {
that.setFirstName(data.first_name);
that.setFullName(data.full_name);
that.setAdress(data.adress);
that.setCountry(data.country);
that.setStamp(data.stamp);
that.setPhoto(data.photo);
that.setSummary(data.summary);
that.setStory(data.story);
that.setMessageText(data.message_text);
that.setDefaultMessageText(data.default_message_text);
that.setMessageImg(data.message_img);
} else {
console.log('failure');
}
}
EDIT The problem might be in my AJAX call, I have to wait till the ajax have been called. but how do I continue the first flow when my Ajax is done and not before?
SOLUTION
I made it working by adding a callback parameter and calling that function in the ajaxs complete function.
$('.case-btn').on('click', function() {
remove_active_state_from_cases();
var that = this;
m_case.setCase($(this).data('case'), function() {
m_postcard.changeBackground(m_case.getPhoto());
m_postcard.changeMessage(m_case.getMessageText());
m_postcard.changeFullName(m_case.getFullName());
m_postcard.changeCountry(m_case.getCountry());
$(that).toggleClass('active');
});
});
// Sets the whole case from an id.
this.setCase = function(id, callback) {
// Set ID
this.setID(id);
var that = this;
$.ajax({
url: 'get_case_by_id.php',
type: 'get',
dataType: 'json',
data: {id: that.getID() },
success: function(data) {
if(data.success) {
that.setFirstName(data.first_name);
that.setFullName(data.full_name);
that.setAdress(data.adress);
that.setCountry(data.country);
that.setStamp(data.stamp);
that.setPhoto(data.photo);
that.setSummary(data.summary);
that.setStory(data.story);
that.setMessageText(data.message_text);
that.setDefaultMessageText(data.default_message_text);
that.setMessageImg(data.message_img);
} else {
console.log('fail big time');
}
},
complete: function() {
callback();
}
});
}
Your m_postcard.changeBackground and other calls should be in the success callback, or in another function that is called from the success callback, as those values aren't set till the async ajax call is done.
With the way your code is now the m_postcard.changeBackground and other calls are called immediately after your setCase function is done executing. This means your methods are executed before the data has arrived from the server
While the ajax is processing you probably should show a loading message on the screen to let the user know they have to wait till the processing is done. Show the message before calling the .ajax call and hide it in the success/error callbacks.
Any changes to the site content should be done from the success callback, ie changing active states, changing content, etc.

getJSON timeout handling

I am using jQuery getJSON() function. This function getting data with no problem. But sometimes waiting, waiting waiting... And my loading bar showing loading loading loadin at center of page.
So jQuery ajax() function have an timeout variable. But i want to use getJSON function. And i think that i can use ajaxStart() and ajaxStop() functions. But how?
$('.loadingDiv')
.hide()
.ajaxStart(function() {
$(this).fadeIn();
setTimeout("throw '';",15000) //i used this but didn't work
setTimeout("return;",15000) //i used this but didn't work
setTimeout("abort();",15000) //i used this but didn't work.(Abort all ajax events)
})
.ajaxStop(function() {
$(this).fadeOut();
});
getJSON() returns a promise on which you can call the abort function :
var p = $.getJSON(..., function(){ alert('success');});
setTimeout(function(){ p.abort(); }, 2000);
EDIT : but if your goal is just to abort if it takes too much time, then lethal-guitar's answer is better.
getJSON() is just a shorthand for the following:
$.ajax({
dataType: "json",
url: url,
data: data,
success: success
});
So you could use $.ajax() and specify the timeout option as desired. See also: http://api.jquery.com/jQuery.getJSON/
As lethal-guitar mentioned getJSON() function is just an shorthand for $.ajax(). If you want to detect if a timeout has occurred rather than an actual error use the code below.
var request = $.ajax({
dataType: "json",
url: url,
data: data,
success: function( ) { },
timeout: 2000
}).fail( function( xhr, status ) {
if( status == "timeout" ) {
// do stuff in case of timeout
}
});
There's always the nuclear route as well:
//Set AJAX timeout to 10 seconds
$.ajaxSetup({
timeout: 10*1000
});
This will set all the AJAX requests your program makes (even via $.getJSON) to have a time out of 10 seconds (or what have you).
the setTimeout function executes a set of code after a specified number of milisecons in the global scope.
The getJSON function (per the jQuery documentation here http://api.jquery.com/jQuery.getJSON/) is shorthand for:
$.ajax({
dataType: "json",
url: url,
data: data,
success: success
});
so you would want to make your call like so:
$.ajax({
dataType: "json",
url: url,
data: data,
success: success,
timeout: 15000
});
$('.loadingDiv')
.hide()
.ajaxStart(function() {
$(this).fadeIn();
})
.ajaxStop(function() {
$(this).fadeOut();
});
I don't think any of these answers are ideal. I know this is years late, but what you want to do is use the success/error callback options of the .ajax(); method when receiving a JSONP response.
Example of how I would structure this:
// Call
$.ajax({
// URL you want to get
url: 'http://example.com/json?callback=?',
// Set a realistic time in milliseconds
timeout: 3000,
// Put in success callback function here, this example
// shows you the data you got back from the call
success: function(data) {
console.log(data);
},
// Put in an error handling function, just an alert in this case
error: function(badData) {
alert('The call was unsuccessful');
},
type: 'POST'
});

How to wait on the __doPostBack method to complete in javascript?

I am using the __doPostBack method to refresh the UpdatePanel in javascript. I just want to wait for the update panel to get updated and then execute the subsequent javascript code. How do I wait on an asynchronous method to complete before I proceed further with execution (like in my case the asynchronous method is __doPostBack)? I want to simulate something like the way it is doing in C# using Thread.Join() method.
Use the Sys.WebForms.PageRequestManager endRequest event:
<script type="text/javascript" language="javascript">
function clearPostBack() {
$get('__EVENTTARGET').value = $get('__EVENTARGUMENT').value = '';
Sys.WebForms.PageRequestManager.getInstance().remove_endRequest(clearPostBack);
// TODO: anything you want after __doPostBack
}
function myPostBack(eventTargetUniqueId, eventArgument) {
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(clearPostBack);
__doPostBack(eventTargetUniqueId, eventArgument);
}
</script>
Here is a much better way, which allows you to do something in case of successfull request and/or error:
$.ajax({
type: "POST",
data:
{
'__EVENTTARGET': '<%=YourButtonName.ClientID %>'
}
}).done(function (data) {
alert("ok");
}).fail(function (p1, p2, p3) {
alert("error");
});

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