Benchmark: JavaScript spread operator vs Object.assign vs for-in loop safe performance

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);
Using For-In loop
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = {} for (let key in firstObject) { finalObject[key] = firstObject[key]; } for (let key in secondObject) { finalObject[key] = secondObject[key]; }
Using For-In loop with hasOwnProperty
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = {} for (let key in firstObject) { if (Object.prototype.hasOwnProperty.call(firstObject, key)) { finalObject[key] = firstObject[key]; } } for (let key in secondObject) { if (Object.prototype.hasOwnProperty.call(secondObject, key)) { finalObject[key] = secondObject[key]; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign
Using For-In loop
Using For-In loop with hasOwnProperty

Fastest: N/A

Slowest: N/A

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Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 16_7 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/122.0.6261.62 Mobile/15E148 Safari/604.1

Browser/OS: Chrome Mobile iOS 122 on iOS 16.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	9263728.0 Ops/sec
Using Object.assign	3761126.0 Ops/sec
Using For-In loop	20671620.0 Ops/sec
Using For-In loop with hasOwnProperty	2368874.0 Ops/sec

JavaScript spread operator vs Object.assign vs for-in loop safe performance (version: 0)

Measure the fastest way to merge objects, without mutation.

Comparing performance of: Using the spread operator vs Using Object.assign vs Using For-In loop vs Using For-In loop with hasOwnProperty

Created: 2 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Using For-In loop

Using For-In loop with hasOwnProperty

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A