Run results for: querySelector vs Loop v4

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.5 Safari/605.1.15

Browser: Safari 15

Operating system: Mac OS X 10.15.6

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
querySelectorAll with .class	571.3 Ops/sec
querySelectorAll with [attribute]	504.6 Ops/sec
filter with classList	72.2 Ops/sec
filter with className	139.6 Ops/sec
filter with getAttribute	320.7 Ops/sec
for with classList	47.1 Ops/sec
for with className	63.9 Ops/sec
for with getAttribute	58.5 Ops/sec
getElementsByClassName	3125723.0 Ops/sec

HTML Preparation code:

<div id="testBody"></div>

Script Preparation code:

const elementCount = 100000;
const body = document.getElementById('testBody');

// Create a Bunch of DOM elements.
// Keep a refrence to all of them to test the other loops.
window.entities = [];
for (let i=0; i < elementCount; i++) {
 let elm = document.createElement('div');
 elm.classList.add(`test-${i%4}`);
 elm.setAttribute(`test`, i%4);
 // Add to body for query selector tests.
 body.appendChild(elm);
 // Add to array for loop tests.
 window.entities.push(elm);
}

Tests:

querySelectorAll with .class
const randomID = 0|Math.random()*4; const result = window.testBody.querySelectorAll(`.test-${randomID}`);
querySelectorAll with [attribute]
const randomID = 0|Math.random()*4; const result = window.testBody.querySelectorAll(`[test="${randomID}"]`);
filter with classList
const randomID = 0|Math.random()*4; const result = window.entities.filter(elm => elm.classList.contains(`test-${randomID}`))
filter with className
const randomID = 0|Math.random()*4; const result = window.entities.filter(elm => elm.className === `test-${randomID}`)
filter with getAttribute
const randomID = 0|Math.random()*4; const result = window.entities.filter(elm => elm.getAttribute('test') === `${randomID}`)
for with classList
const randomID = 0|Math.random()*4; const result = []; for (let i=window.entities.length-1; i >= 0; i--) { const elm = window.entities[i]; if (elm.classList.contains(`test-${randomID}`)) { result.push(elm); } }
for with className
const randomID = 0|Math.random()*4; const result = []; for (let i=window.entities.length-1; i >= 0; i--) { const elm = window.entities[i]; if (elm.className === `test-${randomID}`) { result.push(elm); } }
for with getAttribute
const randomID = 0|Math.random()*4; const result = []; for (let i=window.entities.length-1; i >= 0; i--) { const elm = window.entities[i]; if (elm.getAttribute('test') === `${randomID}`) { result.push(elm); } }
getElementsByClassName
const randomID = 0|Math.random()*4; const result = window.testBody.getElementsByClassName(`test-${randomID}`);

Run results for: querySelector vs Loop v4

If you have a large number of elements, is it faster to use querySelectorAll, or to iterate over an array?

querySelectorAll with .class

querySelectorAll with [attribute]

filter with classList

filter with className

filter with getAttribute

for with classList

for with className

for with getAttribute

getElementsByClassName