Run results for: className vs. setAttribute vs. classList

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/130.0.6723.90 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 130

Operating system: iOS 18.1

Device Platform: Mobile

Date tested: one year ago

className

53K/s

setAttribute

22K/s

classList

22K/s

View exact numbers

Test name	Executions per second
✓ className	53,189 Ops/sec
setAttribute	22,158 Ops/sec
classList	21,556 Ops/sec

HTML Preparation code:

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

Tests:

className
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.className = "bar"; }
setAttribute
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.setAttribute("class", "bar"); }
classList
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.classList.add("bar"); }