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

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_2_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.2 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 18

Operating system: iOS 18.2.1

Device Platform: Mobile

Date tested: one year ago

Benchmark engine: Benchmark.js

concat spread

286K/s

flatMap

194K/s

reduce push

150K/s

forEach push

139K/s

flat

123K/s

reduce

18K/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)