Run results for: JavaScript spread operator vs Object.assign performance

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_3_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/131.0.6778.103 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 131

Operating system: iOS 18.3.0

Device Platform: Mobile

Date tested: one year ago

Using Object.assign

35.9M/s

Using the spread operator

24.8M/s

View exact numbers

Test name	Executions per second
✓ Using Object.assign	35,877,108 Ops/sec
Using the spread operator	24,847,738 Ops/sec

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign(firstObject, secondObject);