Run results for: Transform: Object.fromEntries vs reduce (10000 entries)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36

Browser: Chrome 119

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

Reduce (reuse object)

3K/s

Object.fromEntries (with transform data)

1K/s

Reduce (creating temporary objects)

87/s

View exact numbers

Test name	Executions per second
✓ Reduce (reuse object)	2,513 Ops/sec
Object.fromEntries (with transform data)	1,383 Ops/sec
Reduce (creating temporary objects)	87 Ops/sec

Script Preparation code:

var ENTRIES = 10000;
var data = Array.from(Array(ENTRIES).keys()).map(key => ({id: key, someProp: key + 1}))
var createObject = (value) => ({ id: value.id });

Tests:

Object.fromEntries (with transform data)
Object.fromEntries( data.map( currentObj => { const transformedObj = createObject( currentObj ); return [ transformedObj.id, transformedObj ]; }));
Reduce (reuse object)
data.reduce( ( acc, currentObj ) => { const transformedObj = createObject( currentObj ); acc[ transformedObj.id ] = transformedObj; return acc; }, {});
Reduce (creating temporary objects)
data.reduce( ( acc, currentObj ) => { const transformedObj = createObject( currentObj ); return { ...acc, [ transformedObj.id ]: transformedObj }; }, {} );