Run results for: Reduce: concat vs push vs flatMap

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36

Browser: Chrome 140

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 9 months ago

Reduce + push

167K/s

Flatmap

146K/s

Reduce + concat

15K/s

View exact numbers

Script Preparation code:

a = new Array(1000).fill(0).map(() => ({
    value: Math.random(),
    keep: Math.random() > 0.5
}));

Tests:

Reduce + push
a.reduce((acc, { value, keep }) => { if (keep) { acc.push(value); } return acc; }, []);
Reduce + concat
a.reduce((acc, { value, keep }) => (keep ? acc.concat([value]) : acc), []);
Flatmap
a.flatMap((acc, { value, keep }) => (keep ? [value] : []), []);