Run results for: className.indexOf vs. classList.contains

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:126.0) Gecko/20100101 Firefox/126.0

Browser: Firefox 126

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

className

1.0M/s

classList

557K/s

View exact numbers

Test name	Executions per second
✓ className	1,008,130 Ops/sec
classList	557,314 Ops/sec

HTML Preparation code:

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

Tests:

className
var element = document.getElementById("foo"); var i = 1000; while (i--) { if (element.className.indexOf("test") !== -1) {} }
classList
var element = document.getElementById("foo"); var i = 1000; while (i--) { element.classList.contains("test"); }