Run results for: Add item to array: push vs spread vs assign:

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 17_1_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.1.2 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 17

Operating system: iOS 17.1.2

Device Platform: Mobile

Date tested: 2 years ago

Direct assign an item to an initialized array

9K/s

Push item to an array

8K/s

Append an item by spread

307/s

View exact numbers

Test name	Executions per second
✓ Direct assign an item to an initialized array	8,745 Ops/sec
Push item to an array	8,244 Ops/sec
Append an item by spread	307 Ops/sec

Script Preparation code:

window.MAX_SIZE = 1000;

Tests:

Push item to an array
const items = []; for (let i = 0; i < MAX_SIZE; i++) { items.push(i); }
Append an item by spread
let items = []; for (let i = 0; i < MAX_SIZE; i++) { items = [...items, i]; }
Direct assign an item to an initialized array
const items = new Array(MAX_SIZE); for (let i = 0; i < MAX_SIZE; i++) { items[i] = i; }