Benchmark: flatMap vs reduce vs loop filtering performance vs filter/map

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); }
filter/map
arr.filter((o) => o.assigned).map((o) => o.name);

Rendered benchmark preparation results:

Previous results

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.5 Safari/605.1.15

Browser/OS: Safari 26 on Mac OS X 10.15.7

Related benchmarks:

flatMap vs reduce vs loop filtering performance vs filter/map (version: 1)