Change value on success, but not changing

Question

I need to change the var state on success, but debugging the js code, it doesn't call the success function at all, even though there is success. The state variable remains undefined. I'm not sure why it doesn't change. Looking at the network using firebug, the response is {"d": 1}, which is the value the state should have. Any help is appreciated

var state;

$.ajax({
        url: "isoServe.asmx/GetStatus",
        type: "GET",        
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (msg) {
            state = msg.d;
        }, 
        error: function() {
            alert("Error" );
        }
    }); 

return state;

This question was asked many-many times. Ajax request is executed asynchronously. — Regent, Oct 28 '14 at 14:12

score 0 · Answer 1 · edited Jun 20 '20 at 09:12

0

You should return the state inside the AJAX Call:

var state;

$.ajax({
    url: "isoServe.asmx/GetStatus",
    type: "GET",        
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function (msg) {
        state = msg.d;
        return state;
    }, 
    error: function() {
        alert("Error" );
    }
});

In your case, the return statement fires before the AJAX Response could come! As it says, asynchronous, you need to wait till it gets the response.

Update:

You cannot have a response for the AJAX call directly, as it is an asynchronous request. Instead, it can invoke another function in the success callback, such that the function is triggered and states are set.

edited Jun 20 '20 at 09:12

Community

1
1

answered Oct 28 '14 at 14:12

Praveen Kumar Purushothaman

164,888
24
203
252

Ehm... Return it to where? You actually return it to nowhere... – Regent Oct 28 '14 at 14:12
@Regent Looking at the code, it looks like it is a part inside a function. – Praveen Kumar Purushothaman Oct 28 '14 at 14:13
Yes, it looks so. So that's why I don't understand why you returned it **inside** success callback function. – Regent Oct 28 '14 at 14:14
I explained. Please read the answer again! – Praveen Kumar Purushothaman Oct 28 '14 at 14:15
I have read it multiple times. Once again: what is the point of `return state;` inside success callback function? It returns value to nowhere. For all that I see the idea is to return value from external function, which has this ajax call. – Regent Oct 28 '14 at 14:17
It returns the value to the place, where the original return is there in the OP's post. Agree? – Praveen Kumar Purushothaman Oct 28 '14 at 14:18
Nope. `state` value will be changed on success, but `return state;` just does nothing (doesn't return value to external function). – Regent Oct 28 '14 at 14:21
@Regent So do you know how to make the function return it? – user1960836 Oct 28 '14 at 14:23
@PraveenKumar Hmmm, it will return `undefined`, if it's a function – webdeveloper Oct 28 '14 at 14:23
@PraveenKumar you suggest [this fiddle](http://jsfiddle.net/0o4wa8az/), don't you? – Regent Oct 28 '14 at 14:23
@user1960836 you should call another function when you will get result from server – webdeveloper Oct 28 '14 at 14:28
Unless i just miss-understand the point of your answer, your answer is simply wrong. you can't return from the success callback. – Kevin B Oct 28 '14 at 14:29
1

@user1960836 you can use `$.Deferred()` ([fiddle example](http://jsfiddle.net/0o4wa8az/1/)) or callback function ([fiddle example](http://jsfiddle.net/0o4wa8az/2/)) – Regent Oct 28 '14 at 14:30
@Regent You get an error here: `Failed to load resource: the server responded with a status of 404 (NOT FOUND) ` – Praveen Kumar Purushothaman Oct 28 '14 at 14:34
@PraveenKumar it is not an error: there is no such URL in _jsfiddle.net_, and the code is example. Actually that's why there is returning `-1` with comment **// for JSFiddle** in error callback. – Regent Oct 28 '14 at 14:36

Change value on success, but not changing

1 Answers1

Update: