Run results for: flatten merge array: reduce VS Object.assign

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser: Chrome 122

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Reduce	682735.9 Ops/sec
Object.assign	926961.9 Ops/sec

Script Preparation code:

function createArray(k, propsCount) {
    const arr = []
    for (let i = 0; i < propsCount; i += 1) {
        arr.push({
            id: k * i,
            active: i % 5 === 0
        })
    }
    return arr.reduce((obj, u) =>  ({[u.id]: u}), {})
}

var pages = [createArray(0, 1000),createArray(10,1000),createArray(100,1000)]

Tests:

Reduce
allusers = pages.reduce((store, page) => ({...store, ...page}), {})
Object.assign
allUsers = Object.assign({}, ...pages.flat())

Run results for: flatten merge array: reduce VS Object.assign

Reduce

Object.assign