Run results for: querySelectorAll - vs - getElementsByClassName

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Firefox/68.0

Browser: Firefox 68

Operating system: Windows

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
getElementsByClassName	293416.1 Ops/sec
querySelectorAll	212681.3 Ops/sec

HTML Preparation code:

<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>

Tests:

getElementsByClassName
var foo = document.getElementsByClassName('test') for (var i = 0; i < foo.length; i++) foo[i].dataset.bar
querySelectorAll
var foo = document.querySelectorAll('.test') for (var i = 0; i < foo.length; i++) foo[i].dataset.bar