Repeating setTimeout in a for loop

Question

for (var i = 0; i <= 100; i++) {
  setTimeout(function() {
    celsiusToFahrenheit(i);
  }, 1000);
}

I'd like to make the celsius function run every second for 100 times but somehow it does not work and I have no idea why. Pls halp.

Can you include some details how it doesn't work? Are there any errors? — Daniel_Knights, Jul 05 '20 at 15:38
this is what happens when i run it in the console: https://imgur.com/cokFTw3 — Slom, Jul 05 '20 at 15:40
Simplest solution, change `var` to `let` (check if your environment supports it first) — ibrahim mahrir, Jul 05 '20 at 15:41
Ok nice, ty, but it still does not run the function each second. It runs the whole thing in less than a second — Slom, Jul 05 '20 at 15:43

score 0 · Accepted Answer · answered Jul 05 '20 at 15:41

That loop will create 100 setTimeout that all run at virtually the same time since the loop will complete in a few milliseconds.

Multiply the duration by i to increment it so the durations will be multiples of 1000.

You need to use let instead of var to block scope i

for (let i = 0; i <= 100; i++) {
  setTimeout(function() {
    celsiusToFahrenheit(i);
  }, 1000 * i);
}

1 Answers1