Run results for: querySelectorAll vs getElementsByTagName 24

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.92 Safari/537.36

Browser: Chrome 81

Operating system: Mac OS X 10.15.4

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
querySelectorAll	217345.1 Ops/sec
getElementsByTagName	240762.1 Ops/sec
getElementsByTagName ArrayFrom	249828.1 Ops/sec
getElementsByTagName ForLoop	852788.4 Ops/sec
getElementsByTagName ArrayFilterForEach	190186.9 Ops/sec
getElementsByTagName ArrayFilterMap	189089.1 Ops/sec

HTML Preparation code:

<div>
<img />
<img />
<img />
<img loading /> 
<img loading /> 
<img loading = "lazy" />
</div>
<div>
<img />
<img />
<img />
<img loading /> 
<img loading /> 
<img loading = "lazy" />
</div>

Tests:

querySelectorAll
document.querySelectorAll('img[loading]').forEach(i => { i.setAttribute('loading', 'eager'); });
getElementsByTagName
[...document.getElementsByTagName('img')].forEach(i => { if (typeof i.loading !== "undefined") i.setAttribute('loading', 'eager'); });
getElementsByTagName ArrayFrom
Array.from(document.getElementsByTagName('img')).forEach(i => { if (typeof i.loading !== "undefined") i.setAttribute('loading', 'eager'); });
getElementsByTagName ForLoop
const imgs = document.getElementsByTagName('img'); for (let i = 0; i < imgs.length; i++) { if (typeof imgs[i].loading !== "undefined") imgs[i].setAttribute('loading', 'eager'); }
getElementsByTagName ArrayFilterForEach
[].filter.call(document.getElementsByTagName('img'), i => i.hasAttribute('loading')).forEach(i => i.setAttribute('loading', 'eager'));
getElementsByTagName ArrayFilterMap
[].filter.call(document.getElementsByTagName('img'), i => i.hasAttribute('loading')).map(i => i.setAttribute('loading', 'eager'));

Run results for: querySelectorAll vs getElementsByTagName 24

querySelectorAll

getElementsByTagName

getElementsByTagName ArrayFrom

getElementsByTagName ForLoop

getElementsByTagName ArrayFilterForEach

getElementsByTagName ArrayFilterMap