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/140.0.0.0 Safari/537.36

Browser: Chrome 140

Operating system: Windows

Device Platform: Desktop

Date tested: 11 months ago

getElementsByTagName for existing element

12.1M/s

getElementsByTagName for none existing element

11.8M/s

querySelector for none existing element

7.6M/s

querySelector for existing element

7.3M/s

View exact numbers

Test name	Executions per second
✓ getElementsByTagName for existing element	12,098,690 Ops/sec
getElementsByTagName for none existing element	11,826,432 Ops/sec
querySelector for none existing element	7,602,407 Ops/sec
querySelector for existing element	7,299,822 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');