Benchmark: JavaScript spread operator vs Object.assign performance eo

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);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.163 Safari/537.36

Browser/OS: Chrome 80 on Mac OS X 10.15.4

View result in a separate tab

Test name	Executions per second
Using the spread operator	20588288.0 Ops/sec
Using Object.assign	4712887.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark and explain what's being tested.

**Benchmark Overview**

The MeasureThat.net benchmark compares the performance of two ways to merge objects in JavaScript: using the spread operator (`...`) and `Object.assign()`. The benchmark is designed to measure which approach is faster, but it also provides information about the underlying browser, device platform, operating system, and execution frequency.

**Benchmark Definitions**

The benchmark definition consists of two test cases:

1. **Using the spread operator**: This test case uses the spread operator (`...`) to merge two objects: `firstObject` and `secondObject`. The resulting merged object is stored in the `finalObject`.
```javascript
const firstObject = { sampleData: 'Hello world' }
const secondObject = { moreData: 'foo bar' }
const finalObject = {
  ...firstObject,
  ...secondObject
}
```
2. **Using Object.assign()**: This test case uses the `Object.assign()` method to merge two objects: `firstObject` and `secondObject`. The resulting merged object is stored in the `finalObject`.
```javascript
const firstObject = { sampleData: 'Hello world' }
const secondObject = { moreData: 'foo bar' }
const finalObject = Object.assign({}, firstObject, secondObject)
```
**Comparison of Options**

The benchmark compares the performance of two approaches:

* **Using the spread operator**: This approach is a relatively modern feature in JavaScript that was introduced in ECMAScript 2018 (ES8). It uses the rest and spread syntax (`...`) to create a new object with the properties from `firstObject` and `secondObject`.
* **Using Object.assign()**: This approach has been part of the JavaScript language since ECMAScript 2009 (ES5) and is widely supported by most browsers. It takes an initial value (in this case, an empty object `{}`) and merges the properties from two or more sources.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Using the spread operator**:
	+ Pros: More concise and expressive way to merge objects, modern feature that's widely adopted.
	+ Cons: May not work in older browsers or environments that don't support ES8.
* **Using Object.assign()**:
	+ Pros: Widely supported by most browsers, works in older environments.
	+ Cons: Less concise and less expressive than the spread operator.

**Library Usage**

Neither of these approaches uses a specific library. They are built-in features of the JavaScript language.

**Special JS Features/Syntax**

There is no special JavaScript feature or syntax used in this benchmark. Both test cases use only standard JavaScript syntax.

**Other Alternatives**

If you need to merge objects, there are other alternatives:

* **Array.prototype.reduce()**: You can use `reduce()` to merge two objects.
```javascript
const finalObject = firstObject.reduce((acc, key) => ({ ...acc, [key]: acc[key] }), {})
```
* **JSON.merge()** (ECMAScript 2022): This is a new method introduced in ECMAScript 2022 that allows you to merge two objects.

I hope this explanation helps!

Related benchmarks:

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

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

Created: 4 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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