Run results for: JS insert at index spread vs Splice

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.0.0 Safari/537.36

Browser: Chrome 124

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

Array update with spread operator

2.9M/s

Array update with slice and assign

2.7M/s

View exact numbers

Test name	Executions per second
✓ Array update with spread operator	2,892,276 Ops/sec
Array update with slice and assign	2,702,790 Ops/sec

Script Preparation code:

const ITERATIONS = 500000;
var index = ITERATIONS/2;
var n = Math.random();

var list = [];
for (let i = 0; i < length; i += 1) {
  list.push(Math.random());
}

Tests:

Array update with spread operator
const clone = [ ...list.slice(0, index), n, ...list.slice(index + 1), ];
Array update with slice and assign
const clone = list.slice(); clone[index] = n;