JQuery Reading JSON (global/local variable)

Question

So I'm trying to assign data from JSON to a global variable to use it multiple times later, but I get this problem. First alert passes ok, but for the second one I get cannot read propery 4 of undefined.

  var refference=[]
  $.getJSON('letters.json', function(data) {
              refference=data.letters
              alert(refference[1][4])
        })
  alert(refference[1][4])

Thanks!

You can't. Ajax is asynchronous, the alert on the outside will happen long before the ajax completes. learn.jquery.com/ajax/key-concepts "A is for Asynchronous" — user400654
– user400654, Commented Mar 18, 2013 at 21:59

Amy · Accepted Answer · 2013-03-18 22:02:17Z

5

The second alert(refference[1][4]) will give you an error because at that point in time, the $.getJSON() request has not returned yet. So refference object is still [], therefore property 4 is undefined.

answered Mar 18, 2013 at 22:02

Amy

7,5262 gold badges22 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jack · Accepted Answer · 2013-03-19 07:00:04Z

1

As Kevin B said, the alert is firing before the ajax call is complete. You'd have to put the second alert (or any other function) in the success callback of the ajax request to ensure that it fires after the data is completely loaded.

something like:

$.getJSON('letters.json', function(data) {
              refference=data.letters;
              alert(refference[1][4]);
        }).success(function(){
                    alert(refference[1][4]);
                  });

Here's a working jsFiddle example using a JSON webservice

edited Mar 19, 2013 at 7:00

answered Mar 18, 2013 at 22:04

Jack

1,3528 silver badges16 bronze badges

6 Comments

user400654 Over a year ago

note, your .done() part is invalid and will still alert undefined or throw an error

Jack Over a year ago

yeah, my bad. Should have used 'success. Will update my answer and included a working jsFiddle

user400654 Over a year ago

No, success is depreciated. .done() was correct, but .done(alert(...)) is wrong, so is .success({...})

Jack Over a year ago

Are you sure that "success" is depreciated for getJSON? because according to the jquery API it's not. success({...}) also works fine in the example I posted. (or at least it did until the web service's API's demo limit was exceeded)

Jack Over a year ago

I see what you're saying about success({...}) I fixed that in my fiddle (added function() )but hadn't pasted that into the answer above.

|

Collectives™ on Stack Overflow

JQuery Reading JSON (global/local variable)

2 Answers 2

Comments

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related