Benchmark: lodash merge vs object.assign vs spread

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 };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash merge
object.assign
spread

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
lodash merge	8061067.0 Ops/sec
object.assign	28443918.0 Ops/sec
spread	22788962.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the benchmark.

**What is being tested?**

MeasureThat.net is testing three different approaches for merging two objects in JavaScript:

1. `_.merge` from Lodash library
2. `Object.assign`
3. Spread syntax (`{ ...a, ...b }`)

These approaches are being compared to determine which one is the most efficient.

**Options comparison**

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

### 1. `_`

`.merge` from Lodash library

Pros:

* Well-maintained and widely used
* Supports complex merge logic (e.g., merging arrays, objects with nested properties)

Cons:

* Requires an external dependency (Lodash)
* May have slower startup times due to the dependency

The `_.merge` function takes two objects as input and returns a new merged object. It also supports other data types like arrays.

### 2. `Object.assign`

Pros:

* Built-in JavaScript method, no additional dependencies required
* Simple and straightforward implementation

Cons:

* Only works with objects, not with arrays or other data types
* Can lead to shallow merges if used incorrectly (i.e., merging an object into another object without creating a new target)

`Object.assign` is a built-in JavaScript function that takes multiple targets and an array of key-value pairs as arguments. When used with two objects, it returns a new merged object.

### 3. Spread syntax (`{ ...a, ...b }`)

Pros:

* Native JavaScript syntax, no additional dependencies required
* Works with both objects and arrays

Cons:

* Introduced in ECMAScript 2018 (ES2018), might not be supported by older browsers or environments
* Can lead to slower performance due to the creation of a new object

The spread syntax allows you to create a new object by spreading an existing object's properties onto a target object. When used with two objects, it returns a new merged object.

**Library and syntax features**

Lodash is a popular utility library for JavaScript that provides various functions for tasks like string manipulation, array processing, and more. In this benchmark, `_.merge` is used to merge objects.

The spread syntax (`{ ...a, ...b }`) is a modern JavaScript feature introduced in ECMAScript 2018 (ES2018). It allows you to create a new object by spreading an existing object's properties onto a target object.

**Other alternatives**

If these three approaches are not sufficient for your needs, here are some additional options:

* `Object.create`: can be used to create a new object with the desired properties, but it requires more code and might lead to shallow merges if used incorrectly.
* Custom merge functions: you can write your own custom function to merge objects, but this approach requires more code and expertise.

Keep in mind that the best approach depends on your specific use case, performance requirements, and the environment where your code will run.

Related benchmarks:

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

Comparing performance of: lodash merge vs object.assign vs spread

Created: 6 years ago by: Registered User

Jump to the latest result

lodash merge

object.assign

spread

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):