Run results for: `Array.slice(0, N)` vs `Array.length = N`

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:124.0) Gecko/20100101 Firefox/124.0

Browser: Firefox 124

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

`Array.length = N`

40.5M/s

`Array.slice(0, N)`

15.3M/s

`Object.assign([], arr)` with `Array.length = N`

369K/s

View exact numbers

Test name	Executions per second
✓ `Array.length = N`	40,547,668 Ops/sec
`Array.slice(0, N)`	15,253,723 Ops/sec
`Object.assign([], arr)` with `Array.length = N`	368,645 Ops/sec

Script Preparation code:

var arr = Array.from(Array(100).keys());

Tests:

`Array.slice(0, N)`
arr.slice(0, 20);
`Array.length = N`
arr.length = 20;
`Object.assign([], arr)` with `Array.length = N`
var newArr = Object.assign([], arr); newArr.length = 20;