Benchmark: JavaScript Object Mutation vs Object.assign performance

Tests:

Using Mutation
const baseObject = { } baseObject.sampleData = 'Hello world'; baseObject.moreData = 'foo bar'; const resultObject = baseObject;
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 Mutation
Using Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches to update an object: direct property mutation (`"Using Mutation"` ) and using `Object.assign()` (`"Using Object.assign"`). The test case uses a simple JavaScript object with two properties, which are updated in each approach.

**Direct Property Mutation ("Using Mutation")**

In this approach, the test creates a base object and then updates its `sampleData` and `moreData` properties directly:
```javascript
const baseObject = { }
baseObject.sampleData = 'Hello world'
baseObject.moreData = 'foo bar'

const resultObject = baseObject
```
**Pros:**

1. Simplicity: This approach is straightforward and easy to understand.
2. Low overhead: No additional function calls or object creation are involved.

**Cons:**

1. Performance: Direct property updates can be slower due to the way JavaScript engines optimize property access.
2. Memory usage: Updating properties directly can lead to increased memory allocation, as a new object is not created.

**Object.assign() ("Using Object.assign")**

In this approach, the test creates two separate objects and uses `Object.assign()` to merge them:
```javascript
const firstObject = { sampleData: 'Hello world' }
const secondObject = { moreData: 'foo bar' }
const finalObject = Object.assign(firstObject, secondObject)
```
**Pros:**

1. Performance: `Object.assign()` is optimized for performance and can be faster than direct property updates.
2. Memory efficiency: A new object is created with the updated properties, avoiding unnecessary memory allocation.

**Cons:**

1. Complexity: Using an additional function call and creating a new object can add overhead.
2. Learning curve: This approach may require more understanding of JavaScript's Object Protocol.

**Library Usage**

There is no explicit library usage in this benchmark. However, `Object.assign()` uses the `Object` prototype to provide its functionality.

**Special JS Feature/Syntax**

This benchmark does not use any special JavaScript features or syntax that would affect its performance.

**Alternative Approaches**

Other approaches to updating objects could include:

1. Destructuring assignment: `const { sampleData, moreData } = baseObject`
2. Object literal updates: `{ ...baseObject, sampleData: 'new value' }`
3. Using a library like Lodash's `assignIn()` or `merge()`

Keep in mind that the choice of approach depends on the specific use case and performance requirements.

Let me know if you'd like more information on any of these topics!

Related benchmarks:

JavaScript Object Mutation vs Object.assign performance (version: 0)

Comparing performance of: Using Mutation vs Using Object.assign

Created: 4 years ago by: Guest

Jump to the latest result

Using Mutation

Using Object.assign

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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