Run results for: querySelector vs Loop v4

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 14_4_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 14

Operating system: iOS 14.4.2

Device Platform: Mobile

Date tested: 3 years ago

Test name	Executions per second
querySelectorAll with .class	1271.3 Ops/sec
querySelectorAll with [attribute]	1125.3 Ops/sec
filter with classList	60.4 Ops/sec
filter with className	124.0 Ops/sec
filter with getAttribute	287.4 Ops/sec
for with classList	46.3 Ops/sec
for with className	65.0 Ops/sec
for with getAttribute	80.9 Ops/sec
getElementsByClassName	1892122.6 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