Run results for: JavaScript spread operator vs Object.assign performance (bigger objects)

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36

Browser: Chrome 132

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
Using the spread operator	13793965.0 Ops/sec
Using Object.assign	17301034.0 Ops/sec

Tests:

Using the spread operator
const firstObject = { name: 'Alice', age: 25, contact: { email: 'alice@example.com', phone: '123-456-7890', }, preferences: { language: 'English', timezone: 'UTC', }, }; const secondObject = { job: 'Software Engineer', skills: ['JavaScript', 'React', 'Node.js'], contact: { email: 'alice.work@example.com', }, preferences: { theme: 'dark mode', }, }; const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { name: 'Alice', age: 25, contact: { email: 'alice@example.com', phone: '123-456-7890', }, preferences: { language: 'English', timezone: 'UTC', }, }; const secondObject = { job: 'Software Engineer', skills: ['JavaScript', 'React', 'Node.js'], contact: { email: 'alice.work@example.com', }, preferences: { theme: 'dark mode', }, }; const finalObject = Object.assign(firstObject, secondObject);