Run results for: getElementById vs QuerySelector nested element

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36

Browser: Chrome 137

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

getElementById + firstElementChild

17.6M/s

querySelector

4.4M/s

View exact numbers

Test name	Executions per second
✓ getElementById + firstElementChild	17,646,776 Ops/sec
querySelector	4,422,306 Ops/sec

HTML Preparation code:


<div id="testElmt">
  <p>paragraph</p>
</div>

Tests:

getElementById + firstElementChild
const par = document.getElementById("testElmt").firstElementChild;
querySelector
const par = document.querySelector("#testElmt p");