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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36

Browser: Chrome 123

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

getElementsByClassName

4.2M/s

getElementsByClassName BODY

4.1M/s

querySelector.body

3.7M/s

querySelector

3.6M/s

View exact numbers

Test name	Executions per second
✓ getElementsByClassName	4,175,187 Ops/sec
getElementsByClassName BODY	4,095,302 Ops/sec
querySelector.body	3,656,160 Ops/sec
querySelector	3,584,335 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');