Run results for: className vs. setAttribute vs. classList

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 10_2_1 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) GSA/22.0.141836113 Mobile/14D27 Safari/600.1.4

Browser: Mobile Safari 10

Operating system: iOS 10.2.1

Device Platform: iPhone

Date tested: 7 years ago

Test name	Executions per second
className	27227.2 Ops/sec
setAttribute	15068.1 Ops/sec
classList	10653.4 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"); }