Run results for: Flat map + filter vs. Reduce

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36

Browser: Chrome 123

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

reduce

22K/s

flat map + filter

4K/s

View exact numbers

Test name	Executions per second
✓ reduce	22,396 Ops/sec
flat map + filter	4,240 Ops/sec

Script Preparation code:

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

Tests:

flat map + filter
arr.flatMap((o) => (o.assigned ? [o.name] : [])).filter(Boolean);
reduce
arr.reduce((a, o) => (o.assigned && a.push(o.name), a), [])