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

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; rv:124.0) Gecko/20100101 Firefox/124.0

Browser: Firefox 124

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

Reduce (reuse object)

21K/s

For-of

21K/s

Object.fromEntries

18K/s

Reduce (creating temporary objects)

5K/s

View exact numbers

Test name	Executions per second
✓ Reduce (reuse object)	20,707 Ops/sec
For-of	20,581 Ops/sec
Object.fromEntries	18,076 Ops/sec
Reduce (creating temporary objects)	4,928 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; }