Run results for: test reduce vs flatMap

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.4 Safari/605.1.15

Browser: Safari 16

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
reduce	938.6 Ops/sec
flatMap + filter	1309.6 Ops/sec

Script Preparation code:

window.providerMenuItems = Object.fromEntries(
  Array.from({ length: 1000 }).map((_, id) => [id, { id }]),
);
window.subtreeDishes = new Array(1000).fill(null).map((_, index) => ({
  id: index,
  child_ids: Array.from({ length: 10 }).map(() => Math.floor(Math.random() * 2000)),
}));

Tests:

reduce
subtreeDishes.reduce((res, dish) => { dish.child_ids.forEach((childId) => { if (providerMenuItems[childId]) { res.push(providerMenuItems[childId]); } }); return res; }, []);
flatMap + filter
subtreeDishes .flatMap((dish) => dish.child_ids.map((itemId) => providerMenuItems[itemId])) .filter((val) => val != null);

Run results for: test reduce vs flatMap

reduce

flatMap + filter