Run results for: Reduce with Spread vs Map creation

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36

Browser: Chrome 115

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Flatten array with nested reduce and spread operator	636264.2 Ops/sec
Flatten array with object assignment and forEach	882739.2 Ops/sec

Tests:

Flatten array with nested reduce and spread operator
const things = [{ nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }, { nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }, { nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }, { nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }]; const flatValues = things.reduce((acc, current) => { const nestedValues = current.nestedThings.reduce((acc2, current2) => { return [...acc2, ...current2.key] }, []); return [...acc, ...nestedValues] }, [])
Flatten array with object assignment and forEach
const things = [{ nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }, { nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }, { nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }, { nestedThings: [{ key: 'value' }, { key: 'value' }, { key: 'value' }, { key: 'value' }] }]; const valuesRecord = things.reduce((acc, current, index) => { const nestedValues = current.nestedThings.forEach((nestedThing, index2) => { acc[`${index}-${index2}`] = nestedThing.key; }) return acc; }, {});