Benchmark: Comparing different object merge methods

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: 'foo', b: 'bar' }; var b = { c: 'foobar' }; var c = _.merge(a, b);
object.assign
var a = { a: 'foo', b: 'bar' }; var b = { c: 'foobar' }; var c = Object.assign(a, b);
spread
var a = { a: 'foo', b: 'bar' }; var b = { c: 'foobar' }; var c = { ...a, ...b };
spread mutate
var a = { a: 'foo', b: 'bar' }; var b = { c: 'foobar' }; a = { ...a, ...b };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Lodash merge
object.assign
spread
spread mutate

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Overview**

The benchmark compares different methods for merging two objects in JavaScript: `_.merge` from Lodash, `Object.assign`, and the spread operator (`...`). The benchmark aims to measure which method is the fastest.

**Options Compared**

The four options being compared are:

1. **Lodash merge**: This uses the `_merge` function from the Lodash library to combine two objects.
2. **object.assign**: This uses the `Object.assign()` method to copy and assign properties of one object to another.
3. **spread operator (`...`)**: This uses the spread operator to create a new object with all properties from two source objects.
4. **spread mutate**: This is a variation of the spread operator where the original object's properties are modified instead of creating a new object.

**Pros and Cons**

Here's a brief summary of each option:

* **Lodash merge**:
	+ Pros: Convenient, easy to use, and well-documented.
	+ Cons: Adds an extra dependency (Lodash), can be slower due to the additional function call.
* **object.assign**:
	+ Pros: Built-in method, no dependencies required.
	+ Cons: Can be slower than the spread operator, requires explicitly assigning properties.
* **spread operator (`...`)**:
	+ Pros: Fast, efficient, and easy to use. No extra dependencies required.
	+ Cons: Requires modern JavaScript syntax (ES6+).
* **spread mutate**:
	+ Pros: Similar performance to the spread operator, but modifies the original object instead of creating a new one.
	+ Cons: May be unexpected behavior for some developers.

**Library and Syntax**

The benchmark uses the Lodash library, which provides the `_merge` function. The spread operator (`...`) is a built-in JavaScript syntax that was introduced in ES6.

**Special JS Feature/Syntax**

None of the options use any special JavaScript features or syntax beyond what's required for each method.

**Other Alternatives**

If you're looking for alternative methods to merge objects, consider:

* **concatenating arrays**: While not directly applicable for merging objects, this approach can be used with arrays.
* **using a custom implementation**: You could write your own function for merging objects using a combination of `Object.assign()` and array methods.

**Benchmark Preparation Code**

The provided script preparation code includes a link to the Lodash library (`https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js`), which is used by the benchmark for the `_merge` function.

Overall, this benchmark provides a useful comparison of different methods for merging objects in JavaScript, highlighting the trade-offs between convenience, performance, and syntax requirements.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.97 Safari/537.36

Browser/OS: Chrome 78 on Windows

View result in a separate tab

Test name	Executions per second
Lodash merge	2427725.5 Ops/sec
object.assign	5199293.0 Ops/sec
spread	21060312.0 Ops/sec
spread mutate	20508276.0 Ops/sec

Related benchmarks:

Comparing different object merge methods (version: 0)

Comparing performance of: Lodash merge vs object.assign vs spread vs spread mutate

Created: 4 years ago by: Registered User

Jump to the latest result

Lodash merge

object.assign

spread

spread mutate

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 27 days ago):