Run results for: Spread vs mutating

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3355.0 Safari/537.36

Browser: Chrome 66

Operating system: Linux

Device Platform: Other

Date tested: 2025 years ago

Test name	Executions per second
Spread operator	7.5 Ops/sec
Mutate accumulator	39960.6 Ops/sec

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; }, {});