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

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_5_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/136.0.7103.91 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 136

Operating system: iOS 18.5.0

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
with spread operator	229066.3 Ops/sec
with mutation	3071735.0 Ops/sec
with object assign	305275.3 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