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

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0

Browser: Firefox 102

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
querySelector	4420535.0 Ops/sec
querySelector.body	4147603.2 Ops/sec
getElementsByClassName	9881006.0 Ops/sec
getElementsByClassName BODY	8204361.5 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');