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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.2 Safari/605.1.15

Browser: Safari 26

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 6 months ago

Direct assign an item to an initialized array

1.0M/s

Push item to an array

350K/s

Append an item by spread

765/s

View exact numbers

Test name	Executions per second
✓ Direct assign an item to an initialized array	1,009,222 Ops/sec
Push item to an array	349,953 Ops/sec
Append an item by spread	765 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; }