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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:132.0) Gecko/20100101 Firefox/132.0

Browser: Firefox 132

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: one year ago

Benchmark engine: Benchmark.js

concat spread

142K/s

forEach push

92K/s

reduce push

86K/s

flat

35K/s

flatMap

35K/s

reduce

6K/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)