Benchmark: JavaScript spread operator vs Object.assign performance 26

Tests:

Using the spread operator 23
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject }; let a = 1; if (finalObject !== firstObject) a +=1;
Using Object.assign 22
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign({}, firstObject, secondObject); let a = 1; if (finalObject !== firstObject) a +=1;

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 6.1; Win64; x64; rv:85.0) Gecko/20100101 Firefox/85.0

Browser/OS: Firefox 85 on Windows 7

View result in a separate tab

Test name	Executions per second
Using the spread operator 23	3782144.5 Ops/sec
Using Object.assign 22	3664753.5 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 provided benchmark and explain what's being tested, along with the pros and cons of each approach.

**Benchmark Overview**

The benchmark compares the performance of two methods to merge two objects in JavaScript:

1. The spread operator (`...`).
2. `Object.assign()`.

**Library Used**

In this benchmark, the `Object.assign()` method is used as a library, which is a built-in JavaScript function that copies properties from one or more source objects to a target object.

**Special JS Feature/Syntax**

There's no special JavaScript feature or syntax being tested in this benchmark. The focus is solely on comparing the performance of two methods for merging objects.

**Benchmark Test Cases**

The benchmark consists of two individual test cases:

1. **Using the spread operator**: This test case creates two objects (`firstObject` and `secondObject`) and then uses the spread operator (`...`) to merge them into a new object (`finalObject`). The test also includes an additional condition that checks if the merged object is different from the original `firstObject`. If it's not, the value of variable `a` is incremented by 1.
2. **Using Object.assign()**: This test case creates two objects (`firstObject` and `secondObject`) and then uses `Object.assign()` to merge them into a new object (`finalObject`). Like the first test case, this also includes an additional condition that checks if the merged object is different from the original `firstObject`.

**Pros and Cons of Each Approach**

1. **Spread Operator (`...`)**:
	* Pros:
		+ More concise and readable.
		+ Does not require any libraries or imports.
		+ Can be used with objects, arrays, and other iterable types.
	* Cons:
		+ May have performance overhead due to the creation of a new object.
		+ Not supported in older browsers (IE 11 and below).
2. **Object.assign()**:
	* Pros:
		+ Has been around since ES5 and is widely supported across browsers.
		+ Can be used with objects, arrays, and other iterable types.
	* Cons:
		+ Requires a library or import (in some cases, like in older browsers).
		+ Can lead to unexpected behavior if not used correctly.

**Other Alternatives**

If you're looking for alternatives to the spread operator or `Object.assign()`, consider using:

1. **Rest parameter syntax (`{...obj}`)**: Similar to the spread operator, but uses a rest parameter to create a new object.
2. **ES6 object merge methods (e.g., Object.merge())**: Some libraries and frameworks provide their own implementation of object merging methods.

Keep in mind that while these alternatives exist, they might not offer significant performance benefits over the spread operator or `Object.assign()` for most use cases.

**Additional Considerations**

When choosing between the spread operator and `Object.assign()`, consider the following:

* Use the spread operator when you need to merge objects with a specific format (e.g., merging two objects into a new object with the same structure).
* Use `Object.assign()` when you need to merge objects in a more traditional way, or when you're working with older browsers that don't support the spread operator.

Related benchmarks:

JavaScript spread operator vs Object.assign performance 26 (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):