Run results for: Test spreads1

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/108.0.0.0 Safari/537.36

Browser: Chrome 108

Operating system: Linux

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Test array spread	15.5 Ops/sec
Test array concat	102.5 Ops/sec
Test array push	69067.7 Ops/sec
Test object spread	1567.9 Ops/sec
Test object assign	135.8 Ops/sec

Script Preparation code:

var items = (new Array(1000).fill(0)).map((_, idx) => ({
    id: idx,
    someProp: new Array(),
    also: false,
    maybe: 1,
    hmm: {
        id: idx + 1,
        id2: idx + 1
    }
}))

Tests:

Test array spread
const innerIds = items.reduce((acc, item) => [...acc, item.hmm.id, item.hmm.id2], []);
Test array concat
const innerIds = items.reduce((acc, item) => acc.concat(item.hmm.id, item.hmm.id2), []);
Test array push
const innerIds = items.reduce((acc, item) => { acc.push(item.hmm.id); acc.push(item.hmm.id2); return acc}, []);
Test object spread
const objectSet = items.reduce((acc, item) => ({...acc, [item.id]: item}), {});
Test object assign
const objectSet = items.reduce((acc, item) => Object.assign(acc, {[item.id]: item}), {});

Run results for: Test spreads1

Test array spread

Test array concat

Test array push

Test object spread

Test object assign