Run results for: JavaScript spread operator vs Object.assign performance with big first and small second

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:90.0) Gecko/20100101 Firefox/90.0

Browser: Firefox 90

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Using the spread operator	1510433.0 Ops/sec
Using Object.assign	8021904.0 Ops/sec
Using Object.assign opposite	1482542.0 Ops/sec
Just assignment	24469460.0 Ops/sec

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world', more1: "more1", more2: "more1", more2: "more1", more3: "more1", more4: "more1", more5: "more1", more6: "more1", more7: "more1", more8: "more1", more10: "more1", more20: "more1", more20: "more1", more30: "more1", more40: "more1", more50: "more1", more60: "more1", more70: "more1", more80: "more1", more100: "more1", more200: "more1", more200: "more1", more300: "more1", more400: "more1", more500: "more1", more600: "more1", more700: "more1", more800: "more1" } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world', more1: "more1", more2: "more1", more2: "more1", more3: "more1", more4: "more1", more5: "more1", more6: "more1", more7: "more1", more8: "more1", more10: "more1", more20: "more1", more20: "more1", more30: "more1", more40: "more1", more50: "more1", more60: "more1", more70: "more1", more80: "more1", more100: "more1", more200: "more1", more200: "more1", more300: "more1", more400: "more1", more500: "more1", more600: "more1", more700: "more1", more800: "more1" } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign(firstObject, secondObject);
Using Object.assign opposite
const firstObject = { sampleData: 'Hello world', more1: "more1", more2: "more1", more2: "more1", more3: "more1", more4: "more1", more5: "more1", more6: "more1", more7: "more1", more8: "more1", more10: "more1", more20: "more1", more20: "more1", more30: "more1", more40: "more1", more50: "more1", more60: "more1", more70: "more1", more80: "more1", more100: "more1", more200: "more1", more200: "more1", more300: "more1", more400: "more1", more500: "more1", more600: "more1", more700: "more1", more800: "more1" } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign(secondObject, firstObject);
Just assignment
const firstObject = { sampleData: 'Hello world', more1: "more1", more2: "more1", more2: "more1", more3: "more1", more4: "more1", more5: "more1", more6: "more1", more7: "more1", more8: "more1", more10: "more1", more20: "more1", more20: "more1", more30: "more1", more40: "more1", more50: "more1", more60: "more1", more70: "more1", more80: "more1", more100: "more1", more200: "more1", more200: "more1", more300: "more1", more400: "more1", more500: "more1", more600: "more1", more700: "more1", more800: "more1" } firstObject.moreData = 'foo bar'

Run results for: JavaScript spread operator vs Object.assign performance with big first and small second

Using the spread operator

Using Object.assign

Using Object.assign opposite

Just assignment