How to cancel/abort jQuery AJAX request?
I've an AJAX request which will be made every 5 seconds. But the problem is before the AJAX request if the previous request is not completed I've to abort that request and make a new request.
My code is something like this, how to resolve this issue?
$(document).ready(
var fn = function(){
$.ajax({
url: 'ajax/progress.ftl',
success: function(data) {
//do something
}
});
};
var interval = setInterval(fn, 500);
);
The jquery ajax method returns a XMLHttpRequest object. You can use this object to cancel the request.
The XMLHttpRequest has a abort method, which cancels the request, but if the request has already been sent to the server then the server will process the request even if we abort the request but the client will not wait for/handle the response.
The xhr object also contains a readyState which contains the state of the request(UNSENT-0, OPENED-1, HEADERS_RECEIVED-2, LOADING-3 and DONE-4). we can use this to check whether the previous request was completed.
$(document).ready(
var xhr;
var fn = function(){
if(xhr && xhr.readyState != 4){
xhr.abort();
}
xhr = $.ajax({
url: 'ajax/progress.ftl',
success: function(data) {
//do something
}
});
};
var interval = setInterval(fn, 500);
);
I know this might be a little late but i experience similar issues where calling the abort method didnt really aborted the request. instead the browser was still waiting for a response that it never uses. this code resolved that issue.
try {
xhr.onreadystatechange = null;
xhr.abort();
} catch (e) {}
Why should you abort the request?
If each request takes more than five seconds, what will happen?
You shouldn't abort the request if the parameter passing with the request is not changing. eg:- the request is for retrieving the notification data. In such situations, The nice approach is that set a new request only after completing the previous Ajax request.
$(document).ready(
var fn = function(){
$.ajax({
url: 'ajax/progress.ftl',
success: function(data) {
//do something
},
complete: function(){setTimeout(fn, 500);}
});
};
var interval = setTimeout(fn, 500);
);