Run results for: Cost of adding and removing event listeners

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser: Chrome 135

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Assigning once

2.8M/s

Assigning 1000

3K/s

View exact numbers

Test name	Executions per second
✓ Assigning once	2,803,035 Ops/sec
Assigning 1000	2,782 Ops/sec

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const callbacks = Array.from({ length: 1000 }, () => () => {})
const callback = () => {}

function useEffectCallback(callback) {
  window.addEventListener('keydown', callback);
  window.removeEventListener('keydown', callback);
}

Tests:

Assigning once
useEffectCallback(callback)
Assigning 1000
callbacks.forEach(callback => useEffectCallback(callback))