Benchmark: lodash assign vs lodash merge vs object.assign vs spread vs for loop

HTML Preparation code:


<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Tests:

lodash merge
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = _.merge(a, b);
object.assign
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = Object.assign(a, b);
spread
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = { ...a, ...b };
lodash assign
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = _.assign(a, b);
Good old for loop
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; const merge = (objA, objB) => { const newObject = {}; for (const key in objA) { if (Object.prototype.hasOwnProperty.call(objA, key)) { newObject[key] = objA[key]; } } // eslint-disable-next-line no-restricted-syntax for (const key in objB) { if (Object.prototype.hasOwnProperty.call(objB, key)) { newObject[key] = objB[key]; } } return newObject; };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash merge
object.assign
spread
lodash assign
Good old for loop

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser/OS: Chrome 112 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
lodash merge	3819269.2 Ops/sec
object.assign	7686899.5 Ops/sec
spread	2744127.8 Ops/sec
lodash assign	5284017.0 Ops/sec
Good old for loop	933359296.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares four different ways to merge two objects in JavaScript:

1. `lodash.assign`
2. `_.merge` (a function from the Lodash library)
3. `object.assign`
4. Spread syntax (`{ ... }`)
5. A custom implementation using a for loop

**Options Compared**

Here's a brief summary of each option and their pros and cons:

### 1. `lodash.assign`

* Pros:
	+ Fast and efficient
	+ Well-tested and widely used
* Cons:
	+ Requires an external library (Lodash)
	+ May not be suitable for all use cases

`lodash.assign` is a simple and efficient way to merge two objects. It's implemented in C++ and optimized for performance.

### 2. `_.merge`

* Pros:
	+ Similar to `lodash.assign`, but with more features (e.g., recursively merging nested objects)
	+ Part of the Lodash library, which provides a broad range of utility functions
* Cons:
	+ Requires an external library (Lodash)
	+ May have a higher overhead due to its additional features

`_.merge` is another function from the Lodash library that merges two objects. It's similar to `lodash.assign`, but with more features for handling nested objects.

### 3. `object.assign`

* Pros:
	+ Fast and efficient
	+ Built-in to JavaScript, so no external dependencies required
* Cons:
	+ Only works on objects, not other data types (e.g., arrays)
	+ May not be suitable for all use cases

`object.assign` is a built-in function in JavaScript that merges two objects. It's fast and efficient, but only works on objects.

### 4. Spread syntax (`{ ... }`)

* Pros:
	+ Easy to read and write
	+ No external dependencies required
	+ Works with any data type (e.g., arrays)
* Cons:
	+ May be slower than other methods due to its dynamic nature
	+ Requires modern JavaScript features (ES6+)

Spread syntax is a shorthand way to merge two objects. It's easy to read and write, but may be slower than other methods.

### 5. Custom implementation using a for loop

* Pros:
	+ No external dependencies required
	+ Customizable
* Cons:
	+ May be slower than other methods due to its dynamic nature
	+ Requires manual iteration, which can lead to errors

This custom implementation uses a for loop to merge two objects. It's no-frills and straightforward, but may not be the most efficient or readable solution.

**Library: Lodash**

Lodash is a popular JavaScript library that provides a broad range of utility functions, including `_.merge` and `_.assign`. These functions are designed to work efficiently and effectively with common data structures.

**Special JS Feature/Syntax: None**

There are no special JavaScript features or syntax used in this benchmark. The focus is on comparing the performance of different object merge methods.

In summary, this benchmark compares five different ways to merge two objects in JavaScript. While `lodash.assign` and `_.merge` are fast and efficient, they require an external library (Lodash). `object.assign` is a built-in function that's fast and efficient but only works on objects. Spread syntax is easy to read and write but may be slower than other methods. The custom implementation using a for loop is no-frills but may not be the most efficient or readable solution.

Related benchmarks:

lodash assign vs lodash merge vs object.assign vs spread vs for loop (version: 0)

Comparing performance of: lodash merge vs object.assign vs spread vs lodash assign vs Good old for loop

Created: one year ago by: Guest

Jump to the latest result

lodash merge

object.assign

spread

lodash assign

Good old for loop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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