Benchmark: lodash merge vs object.assign vs spread (v2)

HTML Preparation code:

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

Tests:

lodash merge
var defaultOptions = { headers: { 'content-type': 'application/json', 'user-agent': 'super-app', } }; var options = { headers: {'content-type': 'application/xml' }, data: { 'key': 'value' } }; var result = _.merge(defaultOptions, options);
object.assign
var defaultOptions = { headers: { 'content-type': 'application/json', 'user-agent': 'super-app', } }; var options = { headers: { 'content-type': 'application/xml' }, data: { 'key': 'value' } }; var result = Object.assign(defaultOptions, options);
spread
var defaultOptions = { headers: { 'content-type': 'application/json', 'user-agent': 'super-app', } }; var options = { headers: { 'content-type': 'application/xml' }, data: { 'key': 'value' } }; var result = { ...defaultOptions, ...options };

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: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36

Browser/OS: Chrome 91 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
lodash merge	598884.6 Ops/sec
object.assign	5644771.5 Ops/sec
spread	2289526.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Overview**

The provided benchmark measures the performance of three approaches for merging two objects in JavaScript:

1.  Lodash `merge` function
2.  `Object.assign` method
3.  Spread operator (`...`)

These approaches are compared to determine which one is the most efficient in terms of execution speed.

**Options Compared**

The three options being compared are:

*   **Lodash `merge` function**: This function takes two objects as arguments and returns a new object containing all properties from both objects.
*   **`Object.assign` method**: This method takes multiple target objects and iteratively adds properties from an array of source objects to the target objects. It can be used with two targets (i.e., merging two objects).
*   **Spread operator (`...`)**: This operator creates a new object with all key-value pairs from one or more source objects.

**Pros and Cons of Each Approach**

Here are some pros and cons of each approach:

### Lodash `merge` Function

*   Pros:
    *   Robust implementation that handles edge cases, such as merging arrays.
    *   Can be used for complex object merging scenarios.
*   Cons:
    *   External dependency (Lodash library).
    *   May have additional overhead due to its comprehensive feature set.

### Object.assign Method

*   Pros:
    *   Built-in method in JavaScript, reducing dependencies and performance overhead.
    *   Efficient and lightweight implementation.
*   Cons:
    *   Limited support for certain object types or properties (e.g., symbols).
    *   May require additional setup when merging arrays.

### Spread Operator (`...`)

*   Pros:
    *   Lightweight and efficient implementation with no external dependencies.
    *   Easy to use and intuitive syntax.
*   Cons:
    *   Only works for merging objects; does not support arrays or other complex data types.
    *   Limited control over merge behavior.

**Library Used: Lodash**

Lodash is a popular JavaScript library providing utility functions for various tasks, including object manipulation. In this benchmark, the `merge` function from Lodash is used to compare its performance with the built-in methods and spread operator.

**Special JS Feature/Syntax**

None of the tested approaches use any special JavaScript features or syntax beyond standard language support.

**Alternative Approaches**

Other alternatives for merging objects in JavaScript include:

*   **JSON merge libraries**: Such as jsonmerge.js, which provides a more comprehensive implementation than Lodash's `merge` function.
*   **Custom implementations**: Using recursive functions or other approaches to manually iterate over object properties and assign values.

However, the built-in methods (`Object.assign`) and spread operator are generally considered efficient and lightweight options for simple object merging scenarios.

Related benchmarks:

lodash merge vs object.assign vs spread (v2) (version: 0)

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

Created: 3 years ago by: Guest

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):