Run results for: flatMap vs reduce (concat, spread, append) - MeasureThat.net

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/111.0

Browser: Firefox 111

Operating system: Windows

Device Platform: Desktop

Date tested: 11 months ago

Test name	Executions per second
flatMap	1680.5 Ops/sec
reduce - concat	3.1 Ops/sec
reduce - spread	2.2 Ops/sec
reduce - push	1492.1 Ops/sec

Website performance monitoring

Script Preparation code:

var arr = Array(2000).fill(1).map(() => ({ items: Array(10).fill(1) }))

Tests:

flatMap
arr.flatMap(x => x.items)
reduce - concat
arr.reduce((acc, x) => acc.concat(x.items), [])
reduce - spread
arr.reduce((acc, x) => ([...acc, ...x.items]), [])
reduce - push
arr.reduce((acc, x) => { acc.push(...x.items); return acc; }, [])