Benchmark: JavaScript spread operator vs Object.assign performance: empty src2

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = {} const secondObject = { sampleData: 'Hello world', 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: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.81 Safari/537.36 Edg/94.0.992.50

Browser/OS: Chrome 94 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	2113419.2 Ops/sec
Using Object.assign	5350043.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this benchmark.

**Benchmark Purpose:**
The benchmark is designed to compare the performance of two approaches for merging two objects in JavaScript: using the spread operator (`...`) and `Object.assign`.

**Approaches Compared:**

1. **Spread Operator (`...`):** This approach uses the spread operator to merge the properties of two objects into a new object. The syntax is as follows:
```javascript
const firstObject = { sampleData: 'Hello world' }
const secondObject = { moreData: 'foo bar' }
const finalObject = { ...firstObject, ...secondObject }
```
2. **`Object.assign()` Method:** This approach uses the `Object.assign()` method to merge two objects into a new object. The syntax is as follows:
```javascript
const firstObject = {}
const secondObject = { sampleData: 'Hello world', moreData: 'foo bar' }
const finalObject = Object.assign(firstObject, secondObject)
```
**Pros and Cons of Each Approach:**

1. **Spread Operator (`...`):**
	* Pros:
		+ More concise and readable syntax.
		+ No need to worry about object property order (i.e., `Object.assign()` can alter the original object's properties).
	* Cons:
		+ Can be slower than `Object.assign()` in some cases, due to the overhead of creating a new array of spread values.
2. **`Object.assign()` Method:**
	* Pros:
		+ Faster than the spread operator, especially for large objects or when dealing with performance-critical code.
	* Cons:
		+ Can be less readable and more verbose syntax.

**Library Usage:**
None mentioned in this benchmark.

**Special JavaScript Features/Syntax:**
The benchmark uses the spread operator (`...`), which is a relatively modern feature introduced in ECMAScript 2018 (ES2018). This means that older browsers or environments might not support it, and the benchmark may not be representative of those scenarios.

**Other Alternatives:**
For merging objects, you can also use other approaches, such as:

* Using `Object.create()` and `Object.assign()`: `const finalObject = Object.create(firstObject); Object.assign(finalObject, secondObject)`
* Using a library like Lodash (`_.merge()`): `const finalObject = _.merge({}, firstObject, secondObject)`

However, the spread operator and `Object.assign()` are two of the most common and widely-supported methods for merging objects in JavaScript.

Related benchmarks:

JavaScript spread operator vs Object.assign performance: empty src2 (version: 0)

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

Created: 3 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 2 months ago):