Run results for: spread vs mutation vs Object.assign for reduce callback

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 14_8_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/99.3 Mobile/15E148 Safari/605.1.15

Browser: Mobile Safari 14

Operating system: iOS 14.8.1

Device Platform: Mobile

Date tested: 2 years ago

Test name	Executions per second
with spread operator	419782.8 Ops/sec
with mutation	6756130.0 Ops/sec
with object assign	413755.1 Ops/sec

Tests:

with spread operator
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push(x) } return output } range(0, 10).reduce((acc, num) => { return { ...acc, [num]: num } }, {})
with mutation
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push(x) } return output } range(0, 10).reduce((acc, num) => { acc[num] = num return acc }, {})
with object assign
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push(x) } return output } range(0, 10).reduce((acc, num) => { return Object.assign(acc, {[num]: num}) }, {})

Run results for: spread vs mutation vs Object.assign for reduce callback

with spread operator

with mutation

with object assign