Run results for: className const/cached/new regex, classList contains, className split includes

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36

Browser: Chrome 100

Operating system: Windows

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
className const regex	10335667.0 Ops/sec
className cached regex	3737176.2 Ops/sec
className new regex	3647951.2 Ops/sec
classList contains	10400986.0 Ops/sec
className split includes	3477236.5 Ops/sec

Script Preparation code:

var el = document.createElement('div');
el.className = 'foo bar baz hello world';
var x = 'hello';
var re = new RegExp('\\b' + x + '\\b');
var cache = new Map();

Tests:

className const regex
re.test(el.className);
className cached regex
re = cache.get(x); if (!re) { re = new RegExp('\\b' + x + '\\b'); cache.set(x, re); } re.test(el.className);
className new regex
new RegExp('\\b' + x + '\\b').test(el.className);
classList contains
el.classList.contains(x);
className split includes
el.className.split(' ').includes(x);

Run results for: className const/cached/new regex, classList contains, className split includes

className const regex

className cached regex

className new regex

classList contains

className split includes