Run results for: z-indexes collection and coercion

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_4 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/123.0.6312.52 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 123

Operating system: iOS 17.4

Device Platform: Mobile

Date tested: 7 months ago

Test name	Executions per second
Number + isNaN	2019.4 Ops/sec
Number.parseInt + Number.isInteger	55106.3 Ops/sec
Number.parseInt + simple condition	71738.5 Ops/sec

HTML Preparation code:

<div class="container"></div>

Script Preparation code:

const container = document.querySelector('.container');

const cloneTarget = document.createElement('div');
const listToInsert = document.createElement('div');
listToInsert.id = 'clone-list';

for (let i = 0; i < 100; i++) {
    const clone = cloneTarget.cloneNode(true);
    clone.id = "clone_" + i;
    clone.textContent = 'I am clone ' + i;

    listToInsert.append(clone);
}

container.append(listToInsert);


var elements = document.querySelectorAll('#clone-list *');

Tests:

Number + isNaN
for (let el of elements) { const zIndex = Number(el.style.zIndex); if (!isNaN(zIndex)) { console.log(true); } }
Number.parseInt + Number.isInteger
for (let el of elements) { const zIndex = Number.parseInt(el.style.zIndex, 10); if (Number.isInteger(zIndex)) { console.log(true); } }
Number.parseInt + simple condition
for (let el of elements) { const zIndex = Number.parseInt(el.style.zIndex, 10); if (zIndex || zIndex === 0) { console.log(true); } }

Run results for: z-indexes collection and coercion

Number + isNaN

Number.parseInt + Number.isInteger

Number.parseInt + simple condition