Run results for: Spread vs mutating

Run details:

User agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.186 Safari/537.36

Browser: Chrome 64

Operating system: Windows 7

Device Platform: Other

Date tested: 2025 years ago

Script Preparation code:

var array = Array.from(Array(1000).keys());

Tests:

Spread operator
array.reduce((acc, number) => ({ ...acc, [number]: null }), {});
Mutate accumulator
array.reduce((acc, number) => { acc[number] = null; return acc; }, {});
Object.assign
array.reduce((acc, number) => (Object.assign({}, acc, { [number]: null })))