Run results for: querySelectorAll vs. querySelector + querySelectorAll vs. getElementById + querySelectorAll

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36

Browser: Chrome 142

Operating system: Linux

Device Platform: Desktop

Date tested: 4 months ago

Test name	Executions per second
querySelectorAll	537534.4 Ops/sec
querySelector + querySelectorAll	785614.8 Ops/sec
getElementById + querySelectorAll	853564.1 Ops/sec

HTML Preparation code:

<div id="someId">
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
</div>
<div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
    <div class="someClass"></div>
</div>

Tests:

querySelectorAll
const matches = document.querySelectorAll('#someId .someClass'); matches.forEach(() => {});
querySelector + querySelectorAll
const matches = document.querySelector('#someId').querySelectorAll('.someClass'); matches.forEach(() => {});
getElementById + querySelectorAll
const matches = document.getElementById('someId').querySelectorAll('.someClass'); matches.forEach(() => {});