Run results for: className vs. setAttribute vs. classList

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 15_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/19D52 [FBAN/FBIOS;FBDV/iPhone10,4;FBMD/iPhone;FBSN/iOS;FBSV/15.3.1;FBSS/2;FBID/phone;FBLC/en_GB;FBOP/5]

Browser: Mobile Safari 15

Operating system: iOS 15.3.1

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
className	29915.1 Ops/sec
setAttribute	16749.0 Ops/sec
classList	9633.6 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"); }