Run results for: resize event listener vs resizeObserver

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/110.0

Browser: Firefox 110

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
resizeObserver (body)	3991.6 Ops/sec
resizeObserver (container)	3976.4 Ops/sec
window resize event listener	3720.5 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) }