Run results for: fromEntries vs.reduce vs. forEach

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser: Chrome 126

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Object.fromEntries	360983.5 Ops/sec
Reduce (reuse object)	912376.9 Ops/sec
Reduce (creating temporary objects)	273347.4 Ops/sec
Plain	625320.5 Ops/sec

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;

Run results for: fromEntries vs.reduce vs. forEach

Reduce (creating temporary objects)

Reduce (reuse object)

Object.fromEntries

Plain