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

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 18_3_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/134.0.6998.33 Mobile/15E148 Safari/604.1

Browser: Chrome Mobile iOS 134

Operating system: iOS 18.3.1

Device Platform: Mobile

Date tested: one year ago

Using Object.assign

26.7M/s

Using the spread operator

20.2M/s

View exact numbers

Test name	Executions per second
✓ Using Object.assign	26,744,248 Ops/sec
Using the spread operator	20,156,054 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);