Run results for: Object.fromEntries vs reduce object.assign vs for in

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4.1 Safari/605.1.15

Browser: Safari 17

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

For in

1K/s

Object.fromEntries with Generator

834/s

Object.fromEntries

352/s

Reduce (object assign)

173/s

Reduce (creating temporary objects)

0/s

View exact numbers

Test name	Executions per second
✓ For in	1,208 Ops/sec
Object.fromEntries with Generator	834 Ops/sec
Object.fromEntries	352 Ops/sec
Reduce (object assign)	173 Ops/sec
Reduce (creating temporary objects)	0 Ops/sec

Script Preparation code:

var data = { ...Array.from(Array(10000).keys()) };

Tests:

Object.fromEntries
Object.fromEntries(Object.entries(data).map((key, value) => [key, value]));
Reduce (object assign)
Object.entries(data).reduce((object, [key, value]) => Object.assign(object, { [key]: value }), {})
Reduce (creating temporary objects)
Object.entries(data).reduce((acc, [k, v]) => ({ ...acc, [k]: v.toString() }), {});
For in
const result = {}; for (const key in data) { result[key] = data[key] }
Object.fromEntries with Generator
Object.fromEntries([ ...(function* () { for (const key in data) { yield [key, data[key]]; } })() ]);