Run results for: flat vs flatMap vs reduce vs reduce push vs forEach push vs concat spread

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser: Chrome 129

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Benchmark engine: Benchmark.js

concat spread

240K/s

flat

21K/s

forEach push

21K/s

reduce push

21K/s

flatMap

21K/s

reduce

16K/s

View exact numbers

Script Preparation code:

var arr = Array(100).fill(Array(20).fill(Math.random()*50))

Tests:

reduce
arr.reduce((acc, val) => acc.concat(val), [])
flatMap
arr.flatMap(x => x)
flat
arr.flat()
reduce push
arr.reduce((acc, val) => { if (val) val.forEach(a => acc.push(a)); return acc; }, [])
forEach push
let acc = []; arr.forEach(val => { val && val.forEach(v => acc.push(v)); }), acc;
concat spread
[].concat(...arr)