Run results for: flatMap vs reduce vs loop filtering performance

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:131.0) Gecko/20100101 Firefox/131.0

Browser: Firefox 131

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

loop with push

12K/s

reduce with push

9K/s

flatMap

5K/s

View exact numbers

Script Preparation code:

var arr = Array.from({length:10000}, (v, i) => ({name: i, assigned: Math.random() < 0.5}));

Tests:

flatMap
arr.flatMap((o) => (o.assigned ? [o.name] : []));
reduce with push
arr.reduce((a, o) => (o.assigned && a.push(o.name), a), [])
loop with push
{ const a = []; for (const o of arr) if (o.assigned) a.push(o.name); }