Run results for: querySelector() vs getElementsByTagName()[0] prerun

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36 Edg/136.0.0.0

Browser: Chrome 136

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

getElementsByTagName()[0]

12.6M/s

querySelector

9.0M/s

View exact numbers

Test name	Executions per second
✓ getElementsByTagName()[0]	12,570,460 Ops/sec
querySelector	8,974,338 Ops/sec

HTML Preparation code:

<div>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
  <span></span>
</div>

Script Preparation code:

const div = document.getElementsByTagName('div')[0];
const list = div.getElementsByTagName('span');

Tests:

querySelector
const span = div.querySelector('span');
getElementsByTagName()[0]
const span = list[0]