Run results for: querySelector vs getElementsByTagName simple select

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36

Browser: Chrome 142

Operating system: Linux

Device Platform: Desktop

Date tested: 8 months ago

getElementsByTagName for none existing element

34.0M/s

getElementsByTagName for existing element

33.4M/s

querySelector for existing element

16.6M/s

querySelector for none existing element

16.3M/s

View exact numbers

Test name	Executions per second
✓ getElementsByTagName for none existing element	33,988,644 Ops/sec
getElementsByTagName for existing element	33,432,314 Ops/sec
querySelector for existing element	16,565,502 Ops/sec
querySelector for none existing element	16,327,337 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');