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

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:146.0) Gecko/20100101 Firefox/146.0

Browser: Firefox 146

Operating system: Linux

Device Platform: Desktop

Date tested: 4 months ago

Test name	Executions per second
querySelectorAll	516277.0 Ops/sec
querySelector + querySelectorAll	1659217.8 Ops/sec
getElementById + querySelectorAll	1977799.5 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(() => {});