Run results for: Object.fromEntries vs reduce vs. for-of

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0

Browser: Chrome 120

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

Reduce (reuse object)

16K/s

For-of

15K/s

Object.fromEntries

8K/s

Reduce (creating temporary objects)

1K/s

View exact numbers

Test name	Executions per second
✓ Reduce (reuse object)	15,837 Ops/sec
For-of	15,048 Ops/sec
Object.fromEntries	7,586 Ops/sec
Reduce (creating temporary objects)	1,240 Ops/sec

Script Preparation code:

function rand() {
  return Math.floor(Math.random() * 10000)
}
var data = Array(1000).fill(0).map((_, i) => ({ i, a: rand(), b: rand() }))

Tests:

Object.fromEntries
Object.fromEntries(data.map(({i, ...rest}) => [i, rest]));
Reduce (reuse object)
data.reduce((acc, {i, ...rest}) => { acc[i] = rest; return acc; }, {});
Reduce (creating temporary objects)
Object.entries(data).reduce((acc, {i, ...rest}) => ({ ...acc, [i]: rest }), {});
For-of
const result = {} for (const {i, ...rest} of data) { result[i] = rest; }