Run results for: parent vs document queryselectorAll

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36

Browser: Chrome 100

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
parent.querySelector	897592.6 Ops/sec
document.querySelector	446785.4 Ops/sec
document.querySelector 2	801052.2 Ops/sec

HTML Preparation code:

<div id="main">
<div><div><div><div><div><div>
  
<div id="parent">
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
  <div class="child"></div>
</div>

</div></div></div></div></div></div>
</div>

Script Preparation code:

var main = document.querySelector('#main');
var parent = document.querySelector('#parent');

Tests:

parent.querySelector
var child = parent.querySelectorAll('.child');
document.querySelector
var child = main.querySelectorAll('#parent .child');
document.querySelector 2
var child = main.querySelectorAll('.child');

Run results for: parent vs document queryselectorAll

parent.querySelector

document.querySelector

document.querySelector 2