Run results for: querySelector vs getElementsByTagName simple select

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36

Browser: Chrome 143

Operating system: Windows

Device Platform: Desktop

Date tested: 7 months ago

getElementsByTagName for existing element

24.3M/s

getElementsByTagName for none existing element

23.9M/s

querySelector for none existing element

12.0M/s

querySelector for existing element

11.7M/s

View exact numbers

Test name	Executions per second
✓ getElementsByTagName for existing element	24,316,576 Ops/sec
getElementsByTagName for none existing element	23,931,822 Ops/sec
querySelector for none existing element	11,976,880 Ops/sec
querySelector for existing element	11,650,139 Ops/sec

HTML Preparation code:

<div>
  <test><test2></test2></test>
  <test><test2><test3></test3></test2></test>
  <test></test>
</div>

Tests:

querySelector for existing element
const found = document.querySelector('div');
getElementsByTagName for existing element
const found = document.getElementsByTagName('div');
querySelector for none existing element
const found = document.querySelector('span');
getElementsByTagName for none existing element
const found = document.getElementsByTagName('span');