CODEWITHSUNDEEP
javascript
Oz Harary
Oz Harary

Reputation: 15

function setTimeout in loop

If I use setTimeout in a loop so only after the loop ends it executes all the operation in the same time. I tried to put setTimeout in a separate function, as suggested by many articles, but it does not help. The code is very simple:

function foo(i)
{
    setTimeout( function() {console.log(i);}, 2000);
}

for (let i=0; i<5; i++)
{
    foo(i);
}

It prints 0 1 2 3 4 in one shot

Upvotes: 0

Views: 77

Answers (2)

Bryan Dellinger
Bryan Dellinger

Reputation: 5294

you could also do it with a generator. a generator can pause midway through a function https://www.javascripttutorial.net/es6/javascript-generators/

function* generator() {
    let index = 1;
    while (index <= 5) {
        yield index++;
    }
}

let f = generator();


var interval = window.setInterval(function(){
  const obj = f.next();
   if (obj.done){
   clearInterval(interval);
   } else {
    console.log(obj.value)
   }
}, 1000);

Upvotes: 1

Daniel B.
Daniel B.

Reputation: 181

It's because the proccess registry the 5 setTimeout at almost the same time.

Try with the different timeout time like this:

function foo(i)
{
    setTimeout( function() {console.log(i);}, 1000 * i);
}

for (let i=0; i<5; i++)
{
    foo(i);
}

Upvotes: 1

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