Run results for: className vs. setAttribute vs. classList

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:67.0) Gecko/20100101 Firefox/67.0

Browser: Firefox 67

Operating system: Mac OS X 10.10

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
className	1.4 Ops/sec
classList	12.0 Ops/sec

HTML Preparation code:

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

Tests:

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