No access to global variable from inside a function? (javascript)

Question

This is not the first time I am working with ajax and such, I want to use the jQuery function $.getJSON

I have written the following:

var newIMG;

function random_img(){
    $.getJSON('content/random.php',function (data){
        newIMG = data;
    })      
    alert(newIMG.ERROR);
}

But for some reason I can't access the newIMG variable after the JSON request has been made. Passing it from the $.getJSON function to the random_img() function in some way would be fine as well (better, actually)

It's really strange and I can't figure out what's the problem here.

https://i.sstatic.net/OShao.jpg Screenshot of the firebug console, may explain it better.

Thanks in advance guys.

You are also missing a ; after the })

Hogan
– Hogan

2011-04-09 17:51:10 +00:00
Commented Apr 9, 2011 at 17:51 — Hogan
– Hogan, Commented Apr 9, 2011 at 17:51

EMMERICH · Accepted Answer · 2011-04-09 17:49:13Z

6

It's because you're trying to alert before the JSON request has come back (getJSON is asynchronous) so when it first attempts to alert it, it is undefined.

Move the alert into the callback as such:

$.getJSON('content/random.php',function (data){
  newIMG = data;
  alert(newIMG.ERROR);
});

answered Apr 9, 2011 at 17:49

EMMERICH

3,4842 gold badges21 silver badges15 bronze badges

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

Comments

Gary Chambers · Accepted Answer · 2011-04-09 17:49:31Z

5

Your call to $.getJSON is asynchronous, which means that alert(newIMG.ERROR) will be evaluated before the Ajax call has returned a value. You need to place the alert call inside the callback:

var newIMG;

function random_img(){
  $.getJSON('content/random.php',function (data){
    newIMG = data;
    alert(newIMG.ERROR);
  });      
}

answered Apr 9, 2011 at 17:49

Gary Chambers

25.9k5 gold badges37 silver badges31 bronze badges

1 Comment

CookieMonster Over a year ago

Gosh, why didn't I think of that :L Well, thanks anyway, kind sir

Collectives™ on Stack Overflow

No access to global variable from inside a function? (javascript)

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related