Run results for: resize event listener vs resizeObserver

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_5_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.5 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 17

Operating system: iOS 17.5.1

Device Platform: Mobile

Date tested: 2 days ago

Test name	Executions per second
resizeObserver (body)	2222.2 Ops/sec
resizeObserver (container)	2005.3 Ops/sec
window resize event listener	2108.4 Ops/sec

HTML Preparation code:

<div class="container">
</div>

Tests:

resizeObserver (body)
this._resizeWatcher = new ResizeObserver(entry => { this._onResize(); }); this._resizeWatcher.observe(document.body); function _onResize() { document.querySelector('.container').style.setProperty('--viewport-width', window.innerWidth); } for (let i = 360; i <= 1920; i++) { window.resizeTo(i, 1000) }
resizeObserver (container)
this._resizeWatcher = new ResizeObserver(entry => { this._onResize(); }); this._resizeWatcher.observe(document.querySelector('.container')); function _onResize() { document.querySelector('.container').style.setProperty('--viewport-width', window.innerWidth); } for (let i = 360; i <= 1920; i++) { window.resizeTo(i, 1000) }
window resize event listener
document.querySelector('.container').style.setProperty('--viewport-width', window.innerWidth); window.addEventListener('resize', _onResize); function _onResize() { document.querySelector('.container').style.setProperty('--viewport-width', window.innerWidth); } for (let i = 360; i <= 1920; i++) { window.resizeTo(i, 1000) }