Run results for: className vs classList add,remove

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/139.0.0.0 Safari/537.36

Browser: Chrome 139

Operating system: Windows

Device Platform: Desktop

Date tested: 8 months ago

Test name	Executions per second
className	1419.8 Ops/sec
classList	1057.1 Ops/sec

HTML Preparation code:

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

Tests:

className
var element = document.getElementById("foo"); var i = 1000; while (i--) { if (i % 2 === 0) { element.className += "buzz"; } else { element.className = "fizz"; } }
classList
var element = document.getElementById("foo"); var i = 1000; while (i--) { if (i % 2 === 0) { element.classList.add("buzz"); } else { element.classList.remove("buzz"); } }