How to slow down a loop in JavaScript
I had a loop where I wanted to call an API multiple times, e.g. 500 times.
APIs implement rate limiting and even if not, it’s just unkind to make those many requests in a very short time.
So I wanted to slow down the loop. How?
Turns out it’s pretty simple, once you set up a sleep() function, that you don’t need to change:
const sleep = (milliseconds) => {
return new Promise(resolve => setTimeout(resolve, milliseconds))
}
Then you can call await sleep(1000)
to stop 1 second in every iteration, like this:
const list = [1, 2, 3, 4]
const doSomething = async () => {
for (const item of list) {
await sleep(1000)
console.log('🦄')
}
}
doSomething()
→ Here's my latest YouTube video
→ Get my JavaScript Beginner's Handbook
→ I wrote 17 books to help you become a better developer, download them all at $0 cost by joining my newsletter
→ JOIN MY CODING BOOTCAMP, an amazing cohort course that will be a huge step up in your coding career - covering React, Next.js - next edition February 2025