Benchmark: JavaScript spread operator vs Object.assign performance 2 - kevin

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const finalObject = { ...firstObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const finalObject = Object.assign({}, firstObject);

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: 2 years ago)

User agent: Mozilla/5.0 (Linux; Android 12) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Mobile Safari/537.36

Browser/OS: Chrome Mobile 99 on Android

View result in a separate tab

Test name	Executions per second
Using the spread operator	51952936.0 Ops/sec
Using Object.assign	2538281.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark definition and test cases to understand what is being tested.

**Benchmark Definition:**

The benchmark measures the performance of two approaches to shallowly copy an object in JavaScript:

1. **Using the spread operator (`...`)**: This approach uses the spread operator to create a new object that inherits properties from the original object.
2. **Using `Object.assign()`**: This approach uses the `Object.assign()` method to create a new object by copying properties from the original object.

**Options Compared:**

The benchmark compares two options:

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

**Pros and Cons of Each Approach:**

1. **Using the spread operator (`...`)**:
	* Pros:
		+ Concise and expressive syntax
		+ Efficient, as it creates a new object with references to the original properties
	* Cons:
		+ May not be supported in older browsers or versions of JavaScript
2. **Using `Object.assign()`**:
	* Pros:
		+ Widely supported across different browsers and versions of JavaScript
		+ Can be used for shallow copying, as well as merging objects
	* Cons:
		+ Less concise syntax compared to the spread operator
		+ May create a new object with duplicate property names, leading to unexpected behavior

**Library/Functionality Used:**

None of the test cases use any external libraries or functions other than built-in JavaScript features.

**Special JS Feature/Syntax:**

* The spread operator (`...`) is a relatively recent feature introduced in ECMAScript 2018 (ES2018). It allows for concise object creation and copying.
* `Object.assign()` has been part of the JavaScript standard library since ECMAScript 5 (ES5).

**Other Alternatives:**

1. **`JSON.parse(JSON.stringify(obj))`**: This method creates a deep copy of an object, but it can be slower than shallow copying methods like `Object.assign()`. However, it's useful for creating a deep copy when the original object has cyclic references.
2. **`Array.prototype.slice()` or `Array.prototype.map()`**: These methods can be used to create a new array from a subset of elements in an object, but they're less suitable for shallow copying entire objects.

In summary, the benchmark measures the performance of two approaches to shallowly copy objects in JavaScript: using the spread operator (`...`) and using `Object.assign()`. The choice between these approaches depends on the specific use case, with the spread operator being more concise and efficient but potentially not supported in older browsers or versions of JavaScript.

Related benchmarks:

JavaScript spread operator vs Object.assign performance 2 - kevin (version: 0)

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

Created: 2 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):