Benchmark: JavaScript spread operator vs Object.assign performance 25

Tests:

Using the spread operator 23
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject }; finalObject === firstObject
Using Object.assign 22
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject); finalObject === firstObject

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator 23
Using Object.assign 22

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.190 Safari/537.36

Browser/OS: Chrome 88 on Windows

View result in a separate tab

Test name	Executions per second
Using the spread operator 23	2099689.0 Ops/sec
Using Object.assign 22	4571486.5 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):

LLMs can make mistakes. Check important info.

I'd be happy to explain what's being tested in this JavaScript benchmark.

**Benchmark Test**

The provided benchmark tests two different approaches for merging objects in JavaScript:

1. **Spread Operator (`...`)**: This approach uses the spread operator (`...`) to merge two objects, `firstObject` and `secondObject`, into a new object, `finalObject`. The spread operator takes the properties of an object as arguments to a function.
2. **Object.assign()**: This approach uses the `Object.assign()` method to merge two objects, `firstObject` and `secondObject`, into a new object, `finalObject`.

**Options Compared**

The benchmark compares the performance of these two approaches:

* Using the spread operator (`...`)
* Using `Object.assign()`

**Pros and Cons of Each Approach**

1. **Spread Operator (`...`)**:
	* Pros:
		+ More concise and expressive syntax
		+ No need to create a new object or use `Object.create()`
	* Cons:
		+ Can be slower due to the overhead of creating a new array of properties
		+ Not supported in older browsers (IE 10+, Chrome 4-5, Firefox 3.6-11)
2. **Object.assign()**:
	* Pros:
		+ More widely supported across different browsers and versions
		+ Can be faster due to optimized implementation
	* Cons:
		+ Requires creating a new object or using `Object.create()`
		+ Less concise syntax compared to the spread operator

**Library Usage**

None of these approaches rely on external libraries.

**Special JavaScript Feature/Syntax**

The benchmark uses the rest/spread operator (`...`), which was introduced in ECMAScript 2015 (ES6) as part of a new expression syntax. This feature allows objects to be merged or spread into other objects using the `...` symbol.

**Other Alternatives**

If you're interested in exploring alternative approaches, here are some other options:

1. **Object.create()**: You can use `Object.create()` to create a new object and then assign properties to it.
2. **Array.prototype.push()**: In older browsers (IE 8-9), you could use `Array.prototype.push()` to add properties to an object, but this is not recommended due to performance issues.
3. **Object.assign()` with multiple targets:** You can use `Object.assign()` with multiple targets to merge objects into a single target.

Note that the choice of approach often depends on your specific requirements, such as performance considerations or syntax preferences.

Related benchmarks:

JavaScript spread operator vs Object.assign performance 25 (version: 0)

Comparing performance of: Using the spread operator 23 vs Using Object.assign 22

Created: 3 years ago by: Guest

Jump to the latest result

Using the spread operator 23

Using Object.assign 22

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 2 months ago):