Run results for: querySelector vs getElementsByTagName simple select

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:130.0) Gecko/20100101 Firefox/130.0

Browser: Firefox 130

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

getElementsByTagName for none existing element

12.2M/s

getElementsByTagName for existing element

11.8M/s

querySelector for none existing element

5.7M/s

querySelector for existing element

5.7M/s

View exact numbers

Test name	Executions per second
✓ getElementsByTagName for none existing element	12,158,571 Ops/sec
getElementsByTagName for existing element	11,815,774 Ops/sec
querySelector for none existing element	5,739,138 Ops/sec
querySelector for existing element	5,704,192 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');