Calling variable within jquery function from outside

Question

var test = null;

$.get("/zeWebsite.php?blarg=421", function(data){
    test = data.trim();
});

alert(test);

I always thought declaring the variable from outside the function before hand gave access to the variable even if called within the function. However, my test variable is still alerting as null.

score 4 · Answer 1 · answered Jul 23 '15 at 03:10

4

It is likely an order issue as the $.get function is asynchronous. The callback of the get is not being run until after the alert has already fired.

The alert is being run BEFORE the get has completed. You need to make sure the get is complete before alerting by triggering alert within the callback.

Try:

var test = null;

$.get("/zeWebsite.php?blarg=421", function(data){
    test = data.trim();
    alert(test);
});

or

var test = null;

$.get("/zeWebsite.php?blarg=421", function(data){
    test = data.trim();
    outside();
});

function outside() { alert(test); }

answered Jul 23 '15 at 03:10

Carl K

974
7
18

Ah ok, I get it. So if I ever want to run anything synchronously within javascript I need to call functions within functions. – derpyderp Jul 23 '15 at 05:17
@derpyderp, or you can open somehting like `promises` for self.. – vp_arth Jul 23 '15 at 07:43

vp_arth · Answer 2 · 2015-07-23T07:50:06.600

1

it just not assigned yet..
You can simple wait for it:

var test = null, inprocess = true;

$.get("/zeWebsite.php?blarg=421", function(data){
    test = data.trim();
    inprocess = false;
});

var wait = setInterval(function(){
  if (!inprocess) {
    clearInterval(wait);
    alert(test);
  }
}, 500);

But this code is awful. Much better to trigger callback directly:

var test = null;
$.get("/zeWebsite.php?blarg=421", function(data){
    test = data.trim();
    anyactionwithtest(test);
    alert(test);
});

Or use something like jquery deffered promise:

var test = null;
$.get("/zeWebsite.php?blarg=421", function(data){
    test = data.trim();
}).done(function (data){
   // data also accessible here as is
   alert(test);
});

edited Jul 23 '15 at 07:50

answered Jul 23 '15 at 03:20

vp_arth

14,461
4
37
66

Yes on the second approach, no no no on the first one. – Michael Geary Jul 23 '15 at 04:11
first is just to `why` demonstration... – vp_arth Jul 23 '15 at 07:42

score 0 · Answer 3 · answered Jul 23 '15 at 03:12

0

This is because you are using the variable before the get statement execute completely.

Test will get the value when the get function callback call.

If you place alert in get function then it will call at last.

answered Jul 23 '15 at 03:12

Solutionswithus

149
5

Calling variable within jquery function from outside

3 Answers3