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

Run details:

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:132.0) Gecko/20100101 Firefox/132.0

Browser: Firefox 132

Operating system: Ubuntu

Device Platform: Desktop

Date tested: one year ago

Direct assign an item to an initialized array

475K/s

Push item to an array

458K/s

Append an item by spread

407/s

View exact numbers

Test name	Executions per second
✓ Direct assign an item to an initialized array	475,279 Ops/sec
Push item to an array	458,438 Ops/sec
Append an item by spread	407 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; }