How to make function with an index variable in for cycle?

Question

This question seems super-primitive but I can't figure it out.

I have a code like this. I would expect the result be three alerts "0", "1" and "2". However, that's not what happens - I get three 2s.

for(var i=0; i<3; i++) {

   var j=i;
   setTimeout(function() {

      alert(j);

   },1000);
}

The code is at http://jsfiddle.net/8UMCA/.

How to "fix" the code so it alerts "0"-"1"-"2"?

You need to create a closure: http://stackoverflow.com/questions/111102/how-do-javascript-closures-work — rgthree, Mar 05 '14 at 22:55

score 1 · Answer 1 · answered Mar 05 '14 at 22:49

1

This got it working.

for(var i=0; i<3; i++) {
   setTimeout(function(j) {

      alert(j);

   }(i),1000);
}

answered Mar 05 '14 at 22:49

Karel Bílek

36,467
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94
149

score 1 · Accepted Answer · answered Mar 05 '14 at 22:50

1

Or this

for(var i=0; i<3; i++) {          

       (function(){
             var j=i;
            setTimeout(function() {

            alert(j);

        },1000);           
       }
       )();



   }

answered Mar 05 '14 at 22:50

Toan Nguyen

11,263
5
43
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How to make function with an index variable in for cycle?

2 Answers2