setTimeout doesn't work when closure is included

Question

So I have this piece of code...

 var string = 'qwe';

 document.addEventListener('click', function(e){

    function bar(b){

       var a = string[b];
       if (a == 'q') {
          console.log('first');
       }
       if (a == 'w') {
          console.log('second');
       }
       if (a == 'e') {
          console.log('third');
       }

    }       
    setTimeout( bar(0), 1000 );
});

Problem is setTimeout doesn't work. Code executes right after clicking.

It's weird because if I avoid using the closure, it works...

setTimeout(function bar(){
   var a = string[0];
   //...everything else
},1000 );

But that would probably make the code messy/redundant, since I plan on doing it 3 times. Ideally the working code would be...

setTimeout( bar(0), 1000 );
setTimeout( bar(1), 2000 );
setTimeout( bar(2), 3000 );

But again, setting timeOut like this doesn't work for some reason :/ Any ideas why?

Use `setTimeout( () => bar(0), 1000 )` to queue a function. You just queue the **result** of the function. — Sirko, Sep 01 '17 at 07:21
Your executing the function immediately. 'bar(0)'. Ironically creating a closure would help, but here you have just made a plain function. — Keith, Sep 01 '17 at 07:24
Given `foo(bar())`, `bar` is always executed first and its return value is passed to `foo`. This behavior doesn't magically change for `setTimeout`. — Felix Kling, Sep 01 '17 at 07:27

score 0 · Answer 1 · answered Sep 01 '17 at 07:23

0

setTimeout( bar(0), 1000 );

over here setTimeout expects a function but it gets bar(0). hence while try to initialise bar(0) is called, you have to use

setTimeout( () => bar(0), 1000 )

to make it work, since now it is returning a function

answered Sep 01 '17 at 07:23

marvel308

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Please look for duplicates for such basic questions. Answering a possible dupe can attract unwanted comments/votes – Rajesh Sep 01 '17 at 07:25
yes I see it is a possible duplicate of the question but it also answers why bar(0) was called immediately – marvel308 Sep 01 '17 at 07:30

setTimeout doesn't work when closure is included

1 Answers1