Run results for: MapBy reduce vs foreach

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser: Chrome 131

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

foreach

61.7M/s

reduce

58.2M/s

View exact numbers

Test name	Executions per second
✓ foreach	61,731,360 Ops/sec
reduce	58,235,840 Ops/sec

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const objects = [];
for (let i = 1; i <= count; i++) {
  const obj = {
    id: crypto.randomUUID(),
    name: `object-${i}`
  };
  objects.push(obj);
}

Tests:

reduce
const mapBy = (array, key) => { return array.reduce((acc, item) => { acc[item[key]] = item; return acc; }, {}); } mapBy(objects);
foreach
const mapBy = (array, key) => { const map = {} return array.forEach((item) => { map[item[key]] = item; }); return map } mapBy(objects);