Run results for: flatMap vs reduce (concat) vs reduce (push)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.2 Safari/605.1.15

Browser: Safari 16

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Script Preparation code:

var arr = Array(10_000).fill(1)

Tests:

Reduce concat
arr.reduce((acc, x, index) => acc.concat(x, index % 2 ? x : []), [])
FlatMap
arr.flatMap((x, index) => [x, index % 2 && x]).filter(Boolean)
Reduce push
arr.reduce((acc, x, index) => { acc.push(x); if(index % 2) { acc.push(x) } return acc; }, [])