Benchmark: fromEntries vs.reduce vs. forEach

Script Preparation code:

const CHARS = 'abcdefghijklmnopqrstuvwxyz';
const RANDOM_KEY_LENGTH = 6;
const SAMPLE_SIZE = 200;

function getRandChar() {
    return CHARS.at(Math.floor(Math.random() * CHARS.length));
}

var items = Array.from({
    length: SAMPLE_SIZE
}, (_, index) => `${index}${Array.from({ length: RANDOM_KEY_LENGTH }, getRandChar).join('')}`);

Tests:

Reduce (creating temporary objects)
const result = items.reduce((acc, [item]) => ({ ...acc, [item]: 1 }), {}); return result;
Reduce (reuse object)
const result = items.reduce((acc, item) => { acc[item] = 1; return acc; }, {}); return result;
Object.fromEntries
const result = Object.fromEntries(items.map((item) => [item, 1])); return result;
Plain
const result = {}; items.forEach((item) => { result[item] = 1; }); return result;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Reduce (creating temporary objects)
Reduce (reuse object)
Object.fromEntries
Plain

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36 Edg/126.0.0.0

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
Reduce (creating temporary objects)	52782.8 Ops/sec
Reduce (reuse object)	139551.7 Ops/sec
Object.fromEntries	75299.4 Ops/sec
Plain	118521.5 Ops/sec

Related benchmarks:

fromEntries vs.reduce vs. forEach (version: 3)

Comparing performance of: Reduce (creating temporary objects) vs Reduce (reuse object) vs Object.fromEntries vs Plain

Created: one year ago by: Registered User

Jump to the latest result

Reduce (creating temporary objects)

Reduce (reuse object)

Object.fromEntries

Plain

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A