Run results for: document.querySelector vs document.body.querySelector vs getElementsByClassName

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.99 Safari/537.36 OPR/83.0.4254.27

Browser: Opera 83

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
querySelector	2857640.5 Ops/sec
querySelector.body	2888659.2 Ops/sec
getElementsByClassName	3683834.0 Ops/sec
getElementsByClassName BODY	3349747.8 Ops/sec

HTML Preparation code:

<div class="testElement"></div>

Tests:

querySelector
var el = document.querySelector('.testElement');
querySelector.body
var el = document.body.querySelector('.testElement');
getElementsByClassName
var el = document.getElementsByClassName('testElement');
getElementsByClassName BODY
var el = document.body.getElementsByClassName('testElement');