Run results for: resize event listener vs resizeObserver

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 16_7_8 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.6 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 16

Operating system: iOS 16.7.8

Device Platform: Mobile

Date tested: 5 months ago

Test name	Executions per second
resizeObserver (body)	2077.8 Ops/sec
resizeObserver (container)	2049.9 Ops/sec
window resize event listener	2226.4 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) }