Benchmark: lodash assignIn 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 assign
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; var c = _.assignIn(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 assign
object.assign
spread

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**Overview**

The benchmark compares three methods for merging objects: Lodash's `assignIn`, `object.assign`, and the spread operator (`{ ...a, ...b }`). The test case creates two objects, `a` and `b`, and attempts to merge them using each method, storing the result in variable `c`.

**Library and Purpose**

The library used is Lodash, a popular JavaScript utility library. Specifically, it's used for its `assignIn` function, which merges two objects, allowing you to specify keys that should be updated.

**Special JS Feature or Syntax**

There are no special features or syntax used in this benchmark.

**Benchmark Comparison**

Here's a brief explanation of each approach:

1. **Lodash `assignIn`**: This method merges the properties of object `a` with those of object `b`, allowing you to specify keys that should be updated using the `in` keyword (e.g., `.assignIn(a, b)`). The pros are:
	* It can handle nested objects more elegantly.
	* You have control over which keys are merged and updated.
The cons are:
	* It requires Lodash to be included in your project (which may not be desirable for smaller projects).
2. **`object.assign()`**: This method is a built-in JavaScript function that merges two objects, replacing existing properties with new ones. The pros are:
	* It's a native function, so no additional library is required.
	* It's widely supported across browsers and environments.
The cons are:
	* It can lead to unexpected behavior if you're not careful about which keys are merged.
3. **Spread Operator (`{ ...a, ...b }`)**: This method creates a new object that combines the properties of `a` and `b`. The pros are:
	* It's concise and easy to read.
	* It doesn't require any additional libraries or setup.
The cons are:
	* It can lead to unexpected behavior if you're not careful about which keys are merged.

**Other Considerations**

When choosing a method for merging objects, consider the following:

* If you need more control over the merge process, Lodash `assignIn` might be a better choice.
* If you prefer a native function with minimal additional setup, `object.assign()` is a good option.
* If conciseness and simplicity are key, the spread operator (`{ ...a, ...b }`) can be an attractive choice.

**Alternatives**

If you're not comfortable using Lodash or don't want to use the spread operator, other alternatives for merging objects include:

* `Object.assign()` (as mentioned earlier)
* Using a library like `merge-deep` (which provides more advanced merge functionality)
* Writing a custom function to merge objects
* Using ES6 classes and inheritance to create a new object with merged properties

Related benchmarks:

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

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

Created: 3 years ago by: Guest

Jump to the latest result

lodash assign

object.assign

spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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