Based on some JSON I recieve from an ajax request, I wish to either allow or deny a submit button press (return true/false).
I've attempted to implement a promise, however, I can still see 'product unavailable' is called before I recieve my ajax response.
Is the issue down to it being a form/submit button? Or is this still possible?
var oAH = {
ValidateSubmit : function(self){
// send request to handler
$.ajax({
type: "POST",
url: "",
data: aData,
cache: false})
.done(function(data) {
var oJSON = JSON.parse(data);
if(oJSON.Status === 1){
// return true to allow form to submit
return true;
}else{
console.log('product unavailable (error message)');
return false;
}
})
}
}
// click handler
$('#submitButton').on('click', function(){
return oAH.ValidateSubmit(this);
}
You have number of issues. The most obvious one is that you can't just return from asynchronous code (promise) to use its return value (it's undefined!).
What you need to do is
prevent form submission by default for all cases.
treat promise properly and check returned flag. If it's true, submit form manually using DOM API (form submit method).
make sure you use onsubmit event instead of button onclick.
All together it would look something like this:
var oAH = {
ValidateSubmit: function(self) {
// send request to handler
return $.ajax({
type: "POST",
url: "",
data: aData,
cache: false
})
.then(function(data) { // <----- make sure you use .then
return data.Status === 1;
});
}
}
// form onsubmit handler, form has id form for example, etc.
$('#form').on('submit', function(e) {
var form = this;
e.preventDefault()
return oAH.ValidateSubmit(this)
.then(function(canSubmit) {
if (canSubmit) {
form.submit();
}
});
});
I think what you try to do is not possible. The UI event must be processed at the moment and the ajax request is async.
You could prevent form submiting when clicked, disable button and wait for ajax to return a value and then submit form or not in a callback, something like this:
var oAH = {
ValidateSubmit : function(self){
// send request to handler
$.ajax({
type: "POST",
url: "",
data: aData,
cache: false})
.done(function(data) {
var oJSON = JSON.parse(data);
if(oJSON.Status === 1){
// return true to allow form to submit
submitForm();
}else{
console.log('product unavailable (error message)');
}
})
}
}
function submitForm() {
$('#myForm').submit();
$('#submitButton').removeAttr('disabled');
}
// click handler
$('#submitButton').on('click', function(e){
//prevent submitting
e.preventDefault();
// Disable, you could show a loading animation/gif
$(this).attr('disabled','disabled');
// call ajax
oAH.ValidateSubmit(this);
}
Is it possible that using jQuery, I cancel/abort an Ajax request that I have not yet received the response from?
Most of the jQuery Ajax methods return an XMLHttpRequest (or the equivalent) object, so you can just use abort().
See the documentation:
abort Method (MSDN). Cancels the current HTTP request.
abort() (MDN). If the request has been sent already, this method will abort the request.
var xhr = $.ajax({
type: "POST",
url: "some.php",
data: "name=John&location=Boston",
success: function(msg){
alert( "Data Saved: " + msg );
}
});
//kill the request
xhr.abort()
UPDATE:
As of jQuery 1.5 the returned object is a wrapper for the native XMLHttpRequest object called jqXHR. This object appears to expose all of the native properties and methods so the above example still works. See The jqXHR Object (jQuery API documentation).
UPDATE 2:
As of jQuery 3, the ajax method now returns a promise with extra methods (like abort), so the above code still works, though the object being returned is not an xhr any more. See the 3.0 blog here.
UPDATE 3: xhr.abort() still works on jQuery 3.x. Don't assume the update 2 is correct. More info on jQuery Github repository.
You can't recall the request but you can set a timeout value after which the response will be ignored. See this page for jquery AJAX options. I believe that your error callback will be called if the timeout period is exceeded. There is already a default timeout on every AJAX request.
You can also use the abort() method on the request object but, while it will cause the client to stop listening for the event, it may probably will not stop the server from processing it.
Save the calls you make in an array, then call xhr.abort() on each.
HUGE CAVEAT: You can abort a request, but that's only the client side. The server side could still be processing the request. If you are using something like PHP or ASP with session data, the session data is locked until the ajax has finished. So, to allow the user to continue browsing the website, you have to call session_write_close(). This saves the session and unlocks it so that other pages waiting to continue will proceed. Without this, several pages can be waiting for the lock to be removed.
It's an asynchronous request, meaning once it's sent it's out there.
In case your server is starting a very expensive operation due to the AJAX request, the best you can do is open your server to listen for cancel requests, and send a separate AJAX request notifying the server to stop whatever it's doing.
Otherwise, simply ignore the AJAX response.
AJAX requests may not complete in the order they were started. Instead of aborting, you can choose to ignore all AJAX responses except for the most recent one:
Create a counter
Increment the counter when you initiate AJAX request
Use the current value of counter to "stamp" the request
In the success callback compare the stamp with the counter to check if it was the most recent request
Rough outline of code:
var xhrCount = 0;
function sendXHR() {
// sequence number for the current invocation of function
var seqNumber = ++xhrCount;
$.post("/echo/json/", { delay: Math.floor(Math.random() * 5) }, function() {
// this works because of the way closures work
if (seqNumber === xhrCount) {
console.log("Process the response");
} else {
console.log("Ignore the response");
}
});
}
sendXHR();
sendXHR();
sendXHR();
// AJAX requests complete in any order but only the last
// one will trigger "Process the response" message
Demo on jsFiddle
We just had to work around this problem and tested three different approaches.
does cancel the request as suggested by #meouw
execute all request but only processes the result of the last submit
prevents new requests as long as another one is still pending
var Ajax1 = {
call: function() {
if (typeof this.xhr !== 'undefined')
this.xhr.abort();
this.xhr = $.ajax({
url: 'your/long/running/request/path',
type: 'GET',
success: function(data) {
//process response
}
});
}
};
var Ajax2 = {
counter: 0,
call: function() {
var self = this,
seq = ++this.counter;
$.ajax({
url: 'your/long/running/request/path',
type: 'GET',
success: function(data) {
if (seq === self.counter) {
//process response
}
}
});
}
};
var Ajax3 = {
active: false,
call: function() {
if (this.active === false) {
this.active = true;
var self = this;
$.ajax({
url: 'your/long/running/request/path',
type: 'GET',
success: function(data) {
//process response
},
complete: function() {
self.active = false;
}
});
}
}
};
$(function() {
$('#button').click(function(e) {
Ajax3.call();
});
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="button" type="button" value="click" />
In our case we decided to use approach #3 as it produces less load for the server. But I am not 100% sure if jQuery guarantees the call of the .complete()-method, this could produce a deadlock situation. In our tests we could not reproduce such a situation.
It is always best practice to do something like this.
var $request;
if ($request != null){
$request.abort();
$request = null;
}
$request = $.ajax({
type : "POST", //TODO: Must be changed to POST
url : "yourfile.php",
data : "data"
}).done(function(msg) {
alert(msg);
});
But it is much better if you check an if statement to check whether the ajax request is null or not.
Just call xhr.abort() whether it's jquery ajax object or native XMLHTTPRequest object.
example:
//jQuery ajax
$(document).ready(function(){
var xhr = $.get('/server');
setTimeout(function(){xhr.abort();}, 2000);
});
//native XMLHTTPRequest
var xhr = new XMLHttpRequest();
xhr.open('GET','/server',true);
xhr.send();
setTimeout(function(){xhr.abort();}, 2000);
You can abort any continuous ajax call by using this
<input id="searchbox" name="searchbox" type="text" />
<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script type="text/javascript">
var request = null;
$('#searchbox').keyup(function () {
var id = $(this).val();
request = $.ajax({
type: "POST", //TODO: Must be changed to POST
url: "index.php",
data: {'id':id},
success: function () {
},
beforeSend: function () {
if (request !== null) {
request.abort();
}
}
});
});
</script>
As many people on the thread have noted, just because the request is aborted on the client-side, the server will still process the request. This creates unnecessary load on the server because it's doing work that we've quit listening to on the front-end.
The problem I was trying to solve (that others may run in to as well) is that when the user entered information in an input field, I wanted to fire off a request for a Google Instant type of feel.
To avoid firing unnecessary requests and to maintain the snappiness of the front-end, I did the following:
var xhrQueue = [];
var xhrCount = 0;
$('#search_q').keyup(function(){
xhrQueue.push(xhrCount);
setTimeout(function(){
xhrCount = ++xhrCount;
if (xhrCount === xhrQueue.length) {
// Fire Your XHR //
}
}, 150);
});
This will essentially send one request every 150ms (a variable that you can customize for your own needs). If you're having trouble understanding what exactly is happening here, log xhrCount and xhrQueue to the console just before the if block.
I was doing a live search solution and needed to cancel pending requests that may have taken longer than the latest/most current request.
In my case I used something like this:
//On document ready
var ajax_inprocess = false;
$(document).ajaxStart(function() {
ajax_inprocess = true;
});
$(document).ajaxStop(function() {
ajax_inprocess = false;
});
//Snippet from live search function
if (ajax_inprocess == true)
{
request.abort();
}
//Call for new request
Just use ajax.abort() for example you could abort any pending ajax request before sending another one like this
//check for existing ajax request
if(ajax){
ajax.abort();
}
//then you make another ajax request
$.ajax(
//your code here
);
there is no reliable way to do it, and I would not even try it, once the request is on the go; the only way to react reasonably is to ignore the response.
in most cases, it may happen in situations like: a user clicks too often on a button triggering many consecutive XHR, here you have many options, either block the button till XHR is returned, or dont even trigger new XHR while another is running hinting the user to lean back - or discard any pending XHR response but the recent.
The following code shows initiating as well as aborting an Ajax request:
function libAjax(){
var req;
function start(){
req = $.ajax({
url: '1.php',
success: function(data){
console.log(data)
}
});
}
function stop(){
req.abort();
}
return {start:start,stop:stop}
}
var obj = libAjax();
$(".go").click(function(){
obj.start();
})
$(".stop").click(function(){
obj.stop();
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="button" class="go" value="GO!" >
<input type="button" class="stop" value="STOP!" >
If xhr.abort(); causes page reload,
Then you can set onreadystatechange before abort to prevent:
// ↓ prevent page reload by abort()
xhr.onreadystatechange = null;
// ↓ may cause page reload
xhr.abort();
I had the problem of polling and once the page was closed the poll continued so in my cause a user would miss an update as a mysql value was being set for the next 50 seconds after page closing, even though I killed the ajax request, I figured away around, using $_SESSION to set a var won't update in the poll its self until its ended and a new one has started, so what I did was set a value in my database as 0 = offpage , while I'm polling I query that row and return false; when it's 0 as querying in polling will get you current values obviously...
I hope this helped
I have shared a demo that demonstrates how to cancel an AJAX request-- if data is not returned from the server within a predefined wait time.
HTML :
<div id="info"></div>
JS CODE:
var isDataReceived= false, waitTime= 1000;
$(function() {
// Ajax request sent.
var xhr= $.ajax({
url: 'http://api.joind.in/v2.1/talks/10889',
data: {
format: 'json'
},
dataType: 'jsonp',
success: function(data) {
isDataReceived= true;
$('#info').text(data.talks[0].talk_title);
},
type: 'GET'
});
// Cancel ajax request if data is not loaded within 1sec.
setTimeout(function(){
if(!isDataReceived)
xhr.abort();
},waitTime);
});
This is my implementation based on many answers above:
var activeRequest = false; //global var
var filters = {...};
apply_filters(filters);
//function triggering the ajax request
function apply_filters(filters){
//prepare data and other functionalities
var data = {};
//limit the ajax calls
if (activeRequest === false){
activeRequest = true;
}else{
//abort if another ajax call is pending
$request.abort();
//just to be sure the ajax didn't complete before and activeRequest it's already false
activeRequest = true;
}
$request = $.ajax({
url : window.location.origin + '/your-url.php',
data: data,
type:'POST',
beforeSend: function(){
$('#ajax-loader-custom').show();
$('#blur-on-loading').addClass('blur');
},
success:function(data_filters){
data_filters = $.parseJSON(data_filters);
if( data_filters.posts ) {
$(document).find('#multiple-products ul.products li:last-child').after(data_filters.posts).fadeIn();
}
else{
return;
}
$('#ajax-loader-custom').fadeOut();
},
complete: function() {
activeRequest = false;
}
});
}
I wanted to make an ajax call, and then wait for the response from ajax call (Stop form submission till then) and then post the form based on the ajax response that I get. This question is based on Make ajax call and then submit form. So, after putting below script, everything works fine, but I lose the client side validation. Can I make an ajax call and still respect the Client Side validation?
#section scripts {
<script>
var canSubmit = false;
$('form').submit(function (e) {
if (!canSubmit) {
e.preventDefault();
var data = $('form').serialize();
var url = $(this).data('url');
$.ajax({
url: url,
type: 'POST',
data: data,
success: function (response) {
if (response.hasPreviousRequest) {
if (confirm("You've already applied for this job. Apply again?")) {
canSubmit = true;
$('form').submit();
}
}
else {
canSubmit = true;
$('form').submit();
}
},
error: function () {
alert("error");
}
});
}
});
</script>
}
P.S: Kindly note that as soon I as remove the ajax call Client side validation starts working fine. Can some one please explain me this behaviour?
You need to call the .valid() method on the form element (and if not, then cancel the ajax call)
$('form').submit(function (e) {
if (!$(this).valid()) {
return // exit
}
if (!canSubmit) {
....
I have the following jQuery code, the point of this code is to create a short time delay, so the AJAX request gets time to execute properly:
$('#form_id').submit(function(e) {
e.preventDefault();
$submit_url = $(this).data('submitUrl');
$submit_url = $submit_url.replace('http://','').replace(window.location.host,'');
if ($(this).data('toBeAjaxSubmitted') == true) {
$.ajax($submit_url, {
type : $(this).attr('method'),
data : $(this).serialize(),
complete : function(data) {
$(this).data('toBeAjaxSubmitted', false);
$('#form_id').submit();
}
});
}
});
What happens is, the form starts off with a submit url that I need to submit to in order for the component to save an entry to the database. But I also need user input to submit directly to a payment gateway URL where the user then makes a payment.
The code above creates the AJAX request, but does not return to normal postback behaviour (via $('#form_id').submit()).
It keeps submitting the form over and over, but never posts to the gateway URL or redirects out.
What am I doing wrong?
The following worked for me after some more debugging:
$('#chronoform_Online_Submission_Step8_Payment').submit(function(e) {
var form = this;
e.preventDefault();
$submit_url = $(this).data('submitUrl');
$submit_url = $submit_url.replace('http://','').replace(window.location.host,'');
if ($(this).data('toBeAjaxSubmitted') == true) {
$.ajax($submit_url, {
type : $(this).attr('method'),
data : $(this).serialize(),
complete : function(data, status) {
}
}).done(function() {
form.submit();
});
}
});
What really put me on the wrong path was that in Chrome's Developer Tools I had the following option enabled 'Disable cache (while DevTools is open)' and this was causing some headaches with inconsistent behaviour between Safari, Firefox (which worked) and Chrome which did not.
What about some fiddling with this approach?
$('#form_id').submit(function(e) {
// closures
var $form = $(this);
var fAjaxComplete = function(data) {
// don't send the ajax again
$form.data('toBeAjaxSubmitted', 'false');
// maybe do some form manipulation with data...
// re-trigger submit
$form.trigger('submit');
};
var oAjaxObject = {
type : $form.attr('method'),
data : $form.serialize(),
complete : fAjaxComplete
};
var sSubmitUrl = $form.data('submitUrl');
// scrub url
sSubmitUrl = sSubmitUrl.replace('http://','').replace(window.location.host,'');
// if ajax needed
if ($form.data('toBeAjaxSubmitted') != 'false') {
// go get ajax
$.ajax(sSubmitUrl, oAjaxObject);
// don't submit, prevent native submit behavior, we are using ajax first!
e.preventDefault();
return false;
}
// if you got here, go ahead and submit
return true;
});
I have a procedure running on a timeout to load data in the background:
(function getSubPage() {
setTimeout(function() {
if (cnt++ < pagelist.length) {
loadSubPage(pagelist[cnt]);
getSubPage();
}
}, 500);
})();
In loadSubPage() I'm making $.ajax() calls:
function loadSubPage(page) {
if (typeof(initSubPages[page]) === "undefined") {
$.ajax({
type: "POST",
url: '/Main/GetPageData',
data: { page: page },
success: function (returndata) {
// ...
},
error: function() {
alert("Error retrieving page data.");
}
});
initSubPages[page] = true;
}
}
The problem I'm having is that the error handler is being hit when the user navigates away if any ajax requests are open. I'm trying to get around this by .stop()ing the requests on window.onbeforeunload, but I'm not sure what object to call .stop() on?
jQuery exposes the XMLHttpRequest object's abort method so you can call it and cancel the request. You would need to store the open request into a variable and call abort().
activeRequest = $.ajax({...
and to stop it
activeRequest.abort()
Abort Ajax requests using jQuery
This should come in handy.. You have a jQuery method for doing just that.
The $.ajax returns XMLHTTPRequestObject which has .abort function. This function will halt the request before it completes.
var xhr = $.ajax({ /*...*/
..
..
/* Later somewhere you want to stop*/
xhr.abort();
Read more: How to cancel/abort jQuery AJAX request?
Here is the solution I used based on the feedback:
window.onbeforeunload = function() {
for (page in ajaxing) {
if (ajaxing[page] != null)
ajaxing[page].abort();
}
};
var ajaxing = {};
function loadSubPage(page) {
if (typeof(initSubPages[page]) === "undefined") {
var ajaxRequest = $.ajax({
type: "POST",
url: '/Main/GetPageData',
data: { page: page },
success: function (returndata) {
// ...
},
error: function() {
alert("Error retrieving page data.");
},
complete: function() {
ajaxing[lot] = null;
}
});
ajaxing[page] = ajaxRequest;
initSubPages[page] = true;
}
}