Benchmark: Object.assign vs mutation assign

Tests:

Mutation
let ob = {a:1, b:2}; ob.c = 3;
Object.assign
let ob = {a:1, b:2}; ob = Object.assign(ob, {c:3})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Mutation
Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Windows

View result in a separate tab

Test name	Executions per second
Mutation	111781144.0 Ops/sec
Object.assign	5226937.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the JavaScript microbenchmark on MeasureThat.net.

**Benchmark Description**

The benchmark is designed to compare the performance of two ways to assign new properties to an object in JavaScript:

1. **Mutation Assign**: This method directly modifies the original object by assigning new values to its existing properties.
2. **Object.assign()**: This method creates a shallow copy of the original object and then assigns new values to it.

**Options Compared**

The benchmark compares the performance of these two approaches. The goal is to determine which one is faster, more efficient, or more suitable for different use cases.

**Pros and Cons**

* **Mutation Assign**:
	+ Pros: Simple, straightforward approach that doesn't create a new object.
	+ Cons: Can be slower due to the need to access and modify existing properties. May also cause issues with prototype chains and inheritance.
* **Object.assign()**:
	+ Pros: Creates a shallow copy of the original object, which can help avoid prototype chain collisions. Generally faster than mutation assign due to reduced property lookups.
	+ Cons: Creates an additional object, which may increase memory usage.

**Other Considerations**

When deciding between these approaches, consider the following factors:

* **Prototype Chain**: If you're working with objects that inherit from a common prototype, using Object.assign() can help avoid issues with prototype chain collisions.
* **Memory Usage**: If memory efficiency is crucial, using Object.assign() may be a better choice due to its ability to create a shallow copy of the original object.
* **Performance**: In general, Object.assign() is faster than mutation assign due to reduced property lookups.

**Library and Special JS Feature**

There is no specific library mentioned in this benchmark. However, it's worth noting that some libraries like Lodash or Ramda might have their own implementations of Object.assign() with different optimizations or features.

**Special JS Feature**

This benchmark doesn't use any special JavaScript features beyond the standard syntax for object literals and assignment.

Related benchmarks:

Object.assign vs mutation assign (version: 0)

Comparing performance of: Mutation vs Object.assign

Created: 7 years ago by: Guest

Jump to the latest result

Mutation

Object.assign

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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