Run results for: data attributes versus classes

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
attribute	3431.1 Ops/sec
classes	1515.5 Ops/sec

HTML Preparation code:

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

Script Preparation code:

var element = document.getElementById("foo");
var i = 1000;
while (i--) {
  	element.append(document.createElement('div'));
}

Tests:

attribute
var element = document.getElementById("foo"); for (const div of element.querySelectorAll('div')) { div.setAttribute("data-foo", "1"); } document.querySelectorAll('[data-foo]').forEach(div => div.removeAttribute('data-is-foo'));
classes
var element = document.getElementById("foo"); for (const div of element.querySelectorAll('div')) { div.classList.add("is_foo", "foo_type_1"); } element.querySelectorAll('.is_foo').forEach(element => element.classList.remove('is_foo', 'foo_type_1'));