Run results for: getElementById + getElementByClassName vs querySelector

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.5112.124 YaBrowser/22.9.3.894 Yowser/2.5 Safari/537.36

Browser: Yandex Browser 22

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
getElementById + getElementByClass	2050426.9 Ops/sec
querySelector	1899853.8 Ops/sec

HTML Preparation code:

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

Tests:

getElementById + getElementByClass
var el = document.getElementById('testElement'); var children = el.getElementsByClassName('testElementChild'); var length = children.length;
querySelector
var el = document.querySelector('#testElement .testElementChild'); var length = el.length;