Run results for: className vs classList add and remove

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

className

7K/s

classList

4K/s

View exact numbers

Test name	Executions per second
✓ className	7,041 Ops/sec
classList	4,171 Ops/sec

HTML Preparation code:

<div id="foo"></div>

Tests:

className
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.className += " bar"; element.className = element.className.replace(' bar', ''); }
classList
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.classList.add('bar'); element.classList.remove('bar'); }