Run results for: ResizeObserver vs matchMedia

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_2_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/134.0.6998.99 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 134

Operating system: iOS 18.2.1

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
ResizeObserver	13377.1 Ops/sec
matchMedia	17636.1 Ops/sec

HTML Preparation code:

<div>
  Hello
</div>

Tests:

ResizeObserver
let value; const observer = new ResizeObserver(entries => { value = entries[0].contentRect.width; }) observer.observe(document.body) for (let i = 500; i <= 1920; i++) { window.resizeTo(i, 1000) }
matchMedia
let value; const handleMatchChange = (val) => { value = val; } const match1 = window.matchMedia('screen and (min-width: 800px)') match1.addEventListener('change', handleMatchChange); const match2 = window.matchMedia('screen and (min-width: 480px)') match2.addEventListener('change', handleMatchChange); const match3 = window.matchMedia('screen and (min-width: 1200px)') match3.addEventListener('change', handleMatchChange); for (let i = 500; i <= 1920; i++) { window.resizeTo(i, 1000) }