Run results for: JavaScript spread operator vs Slice/Splice performance, passing

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser: Chrome 135

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Array clone with slice

118.9M/s

Array removal with slice and splice

51.2M/s

Array addition with slice and push

28.1M/s

Array clone with spread operator

24.7M/s

Array addition with spread operator

21.5M/s

Array removal with spread operator

16.8M/s

Array update with spread operator

15.1M/s

View exact numbers

Test name	Executions per second
✓ Array clone with slice	118,929,880 Ops/sec
Array removal with slice and splice	51,222,256 Ops/sec
Array addition with slice and push	28,114,982 Ops/sec
Array clone with spread operator	24,693,186 Ops/sec
Array addition with spread operator	21,538,724 Ops/sec
Array removal with spread operator	16,770,662 Ops/sec
Array update with spread operator	15,066,070 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 clone with spread operator
const clone = [...list];
Array clone with slice
const clone = list.slice();
Array addition with spread operator
const clone = [...list, n];
Array addition with slice and push
const clone = list.slice(); clone.push(n);
Array removal with spread operator
const clone = [ ...list.slice(0, index), ...list.slice(index + 1), ];
Array removal with slice and splice
const clone = list.slice(); clone.splice(index, 1);
Array update with spread operator
const clone = [ ...list.slice(0, index), n, ...list.slice(index + 1), ];