Run results for: className vs. classList (comparing and adding)4

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.183 Safari/537.36 Vivaldi/1.96.1147.42

Browser: Chrome 65

Operating system: Windows

Device Platform: Desktop

Date tested: 6 years ago

Test name	Executions per second
className	2326.9 Ops/sec
classList	752.5 Ops/sec

HTML Preparation code:

<div id="foo" class="folder open filtered"></div>

Tests:

className
var p = document.getElementById("foo"); var i = 1000; while (i--) { if (p.className.indexOf('folder') != -1) p.className = 'folder open'+ (p.className.indexOf('filtered') != -1 ? 'filtered ' : '') +'parent'; }
classList
var p = document.getElementById("foo"); var i = 1000; while (i--) { if(p.classList.contains("folder")) { p.classList.add('open', 'parent'); if (p.className.indexOf('filtered') != -1) p.classList.add('filtered'); } }