Benchmark: _.merge vs _.cloneDeep + Object.assign

HTML Preparation code:

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

Tests:

_.merge
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = _.merge(a, b);
_.cloneDeep + Object.assign
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = _.cloneDeep(b); var d = Object.assign(a, c);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
_.merge
_.cloneDeep + Object.assign

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.88 Safari/537.36

Browser/OS: Chrome 100 on Windows

View result in a separate tab

Test name	Executions per second
_.merge	3400200.8 Ops/sec
_.cloneDeep + Object.assign	1477287.4 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 is being tested.

**Benchmark Overview**

The test case is comparing two approaches for merging objects in JavaScript: Lodash's `_.merge` function and a custom combination of `_.cloneDeep` from Lodash and `Object.assign`. This comparison aims to measure which approach is faster.

**Options Compared**

Two options are compared:

1. **Lodash's _.merge**: A utility function that merges two or more objects into one, overwriting any existing keys.
2. **Custom combination of _.cloneDeep + Object.assign**: This approach first creates a deep copy of the second object using `_.cloneDeep`, and then merges the original object with the cloned copy using `Object.assign`. This is done to ensure that the resulting object has all properties from both input objects.

**Pros and Cons**

* **Lodash's _.merge**:
	+ Pros: Simple, efficient, and well-documented.
	+ Cons: May not preserve certain types of data (e.g., dates) due to inherent limitations in JavaScript's object merging process.
* **Custom combination of _.cloneDeep + Object.assign**:
	+ Pros: Can preserve more data types, especially when dealing with nested objects or arrays. However, this approach is more complex and may introduce additional overhead.
	+ Cons: Requires using an external library (Lodash) and introduces extra steps, which might lead to performance overhead.

**Library Used**

The test case uses Lodash, a popular JavaScript utility library that provides various functions for data manipulation, including object merging (`_.merge`). The `_.cloneDeep` function is used to create a deep copy of an object.

**Special JS Feature/Syntax**

There are no special features or syntax mentioned in the provided code. However, it's worth noting that Lodash's `_.merge` function uses a specific implementation of object merging that might not be immediately familiar to all JavaScript developers.

**Other Alternatives**

If you're interested in exploring alternative approaches for merging objects, here are a few options:

1. **Built-in `Object.assign()`**: You can use the built-in `Object.assign()` method to merge two objects, but this approach has limitations (e.g., it won't preserve certain data types).
2. **ES6 Object Spread Operator (`{ ... }`)**: Introduced in ES6, this syntax allows you to create a new object with spread properties from another object.
3. **Other libraries**: Depending on your specific use case, other libraries like Ramda or Immutable.js might provide more suitable alternatives for object merging.

Keep in mind that the choice of approach depends on the specific requirements and constraints of your project.

Related benchmarks:

_.merge vs _.cloneDeep + Object.assign (version: 0)

Comparing performance of: _.merge vs _.cloneDeep + Object.assign

Created: 2 years ago by: Guest

Jump to the latest result

_.merge

_.cloneDeep + Object.assign

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):