Benchmark: Getting first element using querySelector vs querySelectorAll vs getElementsByClassName

HTML Preparation code:

<div id="test-container"></div>

Script Preparation code:

{
const elementCount = 1000;
const container = window.container = document.getElementById('test-container');
const fragment = document.createDocumentFragment();
const entities = window.entities = [];

for (let i=0; i < elementCount; i++) {
	const element = document.createElement('div');
	element.classList.add(`test-${i%4}`);
	element.setAttribute(`test`, i%4);
 	fragment.append(element);
	entities.push(element);
}
container.append(fragment);
}

Tests:

querySelector()
const randomID = 0|Math.random()*4; const result = window.container.querySelector(`.test-${randomID}`);
querySelectorAll()[0]
const randomID = 0|Math.random()*4; const result = window.container.querySelectorAll(`.test-${randomID}`)[0];
getElementsByClassname()[0]
const randomID = 0|Math.random()*4; const result = window.container.getElementsByClassName(`test-${randomID}`)[0];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
querySelector()
querySelectorAll()[0]
getElementsByClassname()[0]

Fastest: N/A

Slowest: N/A

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Latest run results:

Run details: (Test run date: 25 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:124.0) Gecko/20100101 Firefox/124.0

Browser/OS: Firefox 124 on Windows

View result in a separate tab

Test name	Executions per second
querySelector()	5422679.0 Ops/sec
querySelectorAll()[0]	209542.0 Ops/sec
getElementsByClassname()[0]	5764377.0 Ops/sec

Getting first element using querySelector vs querySelectorAll vs getElementsByClassName (version: 0)

Comparing performance of: querySelector() vs querySelectorAll()[0] vs getElementsByClassname()[0]

Created: 25 days ago by: Guest

Jump to the latest result

querySelector()

querySelectorAll()[0]

getElementsByClassname()[0]

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A