Run results for: test children matches vs classList vs querySelectorAll vs getElementsByClassName

Run details:

User agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:109.0) Gecko/20100101 Firefox/115.0

Browser: Firefox 115

Operating system: Windows 8.1

Device Platform: Desktop

Date tested: one year ago

getElementsByClassName

1041.3M/s

querySelectorAll

33K/s

className

6K/s

classList

6K/s

matches

5K/s

View exact numbers

Test name	Executions per second
✓ getElementsByClassName	1,041,310,656 Ops/sec
querySelectorAll	33,463 Ops/sec
className	5,555 Ops/sec
classList	5,533 Ops/sec
matches	4,543 Ops/sec

HTML Preparation code:

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

Script Preparation code:

const count = 1000;
const holder = document.getElementById('test');

for (let i = 0; i < count; i++) {
   let elem = document.createElement('div');
   elem.classList.add(0|Math.random()*2 ? 'foo' : 'bar');
   holder.appendChild(elem);
}

Tests:

matches
const result = Array.from(holder.children).filter((node) => node.matches('.foo'));
classList
const result = Array.from(holder.children).filter((node) => node.classList.contains('foo'));
className
const result = Array.from(holder.children).filter((node) => node.className.includes('foo'));
querySelectorAll
const result = holder.querySelectorAll(':scope > .foo');
getElementsByClassName
const result = holder.getElementsByClassName('foo');