Benchmark: spread vs assign vs _.merge

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 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
lodash merge	8067011.0 Ops/sec
object.assign	9591334.0 Ops/sec
spread	41426172.0 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 provided benchmark and explain what's being tested, along with the pros and cons of each approach.

**Benchmark Overview**

The benchmark measures the performance of three different ways to merge two objects in JavaScript: `_.merge` (from the Lodash library), `Object.assign()`, and the spread operator (`...`).

**Test Cases**

Each test case consists of a brief description of how the object merging is performed, followed by the name of the benchmark. The tests are:

1. `lodash merge`: Merges two objects using Lodash's `merge()` function.
2. `object.assign()`: Merges two objects using the `Object.assign()` method.
3. `spread`: Merges two objects using the spread operator (`...`).

**Library: Lodash**

Lodash is a popular JavaScript utility library that provides a wide range of functions for common tasks, such as string manipulation, array manipulation, and object manipulation. The `merge()` function in Lodash takes two objects as arguments and returns a new object containing all properties from both input objects.

**Pros and Cons of Each Approach**

1. **_.merge (Lodash)**:
	* Pros: Robust implementation with built-in support for many edge cases, such as arrays and null values.
	* Cons: Add an extra dependency on the Lodash library, which may not be desirable in all situations.
2. **Object.assign()**:
	* Pros: Native JavaScript method that doesn't require any external libraries, making it a simple choice.
	* Cons: Can lead to issues with nested arrays or objects, as well as potential security concerns due to its use of the `eval()` function for deep merging (although this is not enabled by default).
3. **Spread Operator (`...`)**:
	* Pros: Simple and intuitive way to merge objects, with no additional dependencies.
	* Cons: Not supported in older browsers or environments that don't support ES6+ syntax.

**Other Considerations**

When choosing an object merging approach, consider the following factors:

* Performance: `_.merge()` may be faster due to its optimized implementation, while `Object.assign()` can lead to slower performance due to its use of `eval()`. The spread operator is generally fast but may not be as performant in all cases.
* Complexity: If you need to merge objects with nested arrays or complex structures, `_.merge()` may be a better choice. Otherwise, the spread operator or `Object.assign()` might suffice.

**Alternatives**

If you're interested in exploring other object merging approaches, consider:

1. **JSON Merge Patch**: A library that provides a more efficient and flexible way to merge objects.
2. **Deep Copy**: Use a library like Lodash's `cloneDeep()` or the `lodash.extend` method with the `deep: true` option to create a deep copy of an object.
3. **Manual Merging**: Implement your own manual merging logic using nested loops and conditional statements.

These alternatives may offer better performance, flexibility, or simplicity depending on your specific use case.

Related benchmarks:

spread vs assign vs _.merge (version: 0)

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

Created: 7 years ago by: Registered User

Jump to the latest result

lodash merge

object.assign

spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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