Run results for: className vs. setAttribute vs. classList

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 12_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.3.1 Mobile/15E148 Safari/604.1 Lark/3.23.0 LarkLocale/zh_CN

Browser: Mobile Safari 12

Operating system: iOS 12.3.1

Device Platform: Mobile

Date tested: 4 years ago

Test name	Executions per second
className	31873.4 Ops/sec
setAttribute	18861.9 Ops/sec
classList	13319.8 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"); }