calling jquery ajax function from javascript [duplicate]

Question

Possible Duplicate:
jQuery ajax return value
How to return the response from an AJAX call from a function?

I have javascript. It loads data from database. I want to return true or false with respect to loading data. But I could not return it. My code has given bellow:

function CheckISRC() {
     var url = "/TrackEdit/CheckISRC/" + $('#isrcid').val();
     var isrc = $('#isrcid').val();
     var result = false;
     $.get(url, {
         isrc: isrc
     }, function (data) {
         if (data == "true") {
             result = true;
         }
         else {
             result = false;
         }
     });
     return result;
 }

It always gives false result. Anyone has faced this kind of problem? 'Thanks advance'

Have you checked whether the response from the database is equal to "true"? You can do this via Firebug, Chrome Developer Tool, or IE Developer Tool. — rink.attendant.6
– rink.attendant.6, Commented Jan 21, 2013 at 13:55
Thats because .get is asynchronous by default - you should read about async and callbacks. — techfoobar
– techfoobar, Commented Jan 21, 2013 at 13:55
Anyone has faced this kind of problem? at least 3 people every day ;) — Felix Kling
– Felix Kling, Commented Jan 21, 2013 at 14:18
@FelixKling perfect link ... that should be the reference for these questions — Manse
– Manse, Commented Jan 21, 2013 at 14:22

Minko Gechev · Accepted Answer · 2013-01-21 13:55:39Z

0

If it's so important to use the function synchronously you can refactor it to:

function CheckISRC() {
     var url = "/TrackEdit/CheckISRC/" + $('#isrcid').val();
     var isrc = $('#isrcid').val();
     var result = false;
     $.ajax({
        async: false,
        success: function (data) {
           if (data == "true") {
               result = true;
           }
           else {
               result = false;
           }
         },
         data: { isrc: isrc }
     });
     return result;
 }

As @ManseUK async is deprecated in jQuery 1.8 so if you want synchronous approach you should use older version.

answered Jan 21, 2013 at 13:55

Minko Gechev

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9 Comments

Manse Over a year ago

async: false is deprecated as of jQuery 1.8

Minko Gechev Over a year ago

Ok, then he should use previous version :-)

Manse Over a year ago

Nope the OP should use the function properly and use a callback

Minko Gechev Over a year ago

He should but I cant force him to do it.

Felix Kling Over a year ago

deprecated does not mean it's removed. And to be correct, only the use of async: false together with deferred objects is deprecated, at least that's how I understand the documentation. But that does not change the fact the making synchronous calls is a really bad idea.

|

Hosein · Accepted Answer · 2013-01-21 13:56:53Z

0

The problem is that when you return result, It doesnt have value. because the ajax didn't finish its task. you make some callback function and when the result of ajax is returned from server, do what you want to.

Some thing like this:

function CheckISRC(Callback) {
    var url = "/TrackEdit/CheckISRC/" + $('#isrcid').val();
    var isrc = $('#isrcid').val();
    var result = false;
    $.get(url, {
        isrc: isrc
    }, function (data) {
        if (data == "true") {
            Callback(true);
        }
        else {
            Callback(false);
        }
    });
 }
 function YourCallback(result) {
     //...
 }

answered Jan 21, 2013 at 13:56

Hosein

5911 gold badge7 silver badges29 bronze badges

Comments

jaypeagi · Accepted Answer · 2013-01-21 14:00:54Z

0

The JQuery ajax functions are asynchronous. This means that when you initialise result to false, the result is set to true or false after the "return result;" line has run.

You can make the call synchronous but this is considered worse practice. You are often better off refactoring your code to allow for the asynchronous nature of the JQuery Ajax.

For example, where you previously had:

function myFunction() {
    //Code before
    var result = CheckISRC();
    //Code after using result
}

you could have the following:

function myFunction() {
    //Code before
    CheckISRC();
}
function myFunction_callback(result) {
    //Code after using result
}

where you call myFunction_callback in the success option of your ajax code like so:

function CheckISRC() {
     var url = "/TrackEdit/CheckISRC/" + $('#isrcid').val();
     var isrc = $('#isrcid').val();
     $.get(url, {
         isrc: isrc
     }, function (data) {
             myFunction_callback(data == "true");
     });
 }

edited Jan 21, 2013 at 14:00

answered Jan 21, 2013 at 13:55

jaypeagi

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5 Comments

user1928185 Over a year ago

[jaypeagi] thank you for your reply. It would be work. I have one more problem. It gives result after from submission. But I call it before from submission. I need result before submssion

jaypeagi Over a year ago

If you are calling CheckISRC before a form submits, you will have to somehow cancel the submission before calling it, then trigger the submission manually in the callback function.

jaypeagi Over a year ago

It may be best for your code to fire in an onclick event rather than on submit. Then you could submit the form manually in JavaScript. Check out JQuerys submit function: api.jquery.com/submit

user1928185 Over a year ago

thank you very much. Finally I solved it by focusout.

jaypeagi Over a year ago

Glad to have helped. Please mark as answer if it solved your problem. Thanks.

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