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

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser: Chrome 134

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Direct assign an item to an initialized array

492K/s

Push item to an array

248K/s

Append an item by spread

2K/s

View exact numbers

Test name	Executions per second
✓ Direct assign an item to an initialized array	492,057 Ops/sec
Push item to an array	247,614 Ops/sec
Append an item by spread	1,896 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; }