Benchmark: lodash assignIn vs object.assign vs spread vs loop

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 };
For loop
var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; for (const key in b) { a[key] = b[key] }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
lodash assign
object.assign
spread
For loop

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 is being tested, compared options, pros and cons of each approach, library usage, special JavaScript features or syntax, and alternatives.

**Benchmark Overview**

The benchmark measures the performance of four different approaches to merge two objects: `_.assignIn` from Lodash, `Object.assign`, spread operator (`{ ...a, ...b }`), and a loop using `for...in`.

**Tested Options**

1. **Lodash `assignIn`**: This function assigns values from an object to a target object, using the property names of the source object as keys.
2. **`Object.assign`**: This method creates a new object with the properties of two or more given objects.
3. **Spread Operator (`{ ...a, ...b }`)**: This operator creates a new object by copying all enumerable own properties from one or more source objects into a new object.
4. **Loop using `for...in`**: A traditional loop that iterates over the properties of an object and assigns values to a target object.

**Pros and Cons of Each Approach**

1. **Lodash `assignIn`**:
	* Pros: Fast, efficient, and easy to use with multiple source objects.
	* Cons: Requires Lodash library, may not be suitable for all use cases (e.g., merging two simple objects).
2. **`Object.assign`**:
	* Pros: Simple, widely supported, and works with any object type.
	* Cons: Can be slower than `assignIn`, especially when dealing with large numbers of properties or complex objects.
3. **Spread Operator (`{ ...a, ...b }`)**:
	* Pros: Fast, modern, and easy to read.
	* Cons: Requires ES6+ support, may not work in older browsers or environments.
4. **Loop using `for...in`**:
	* Pros: Portable across all JavaScript environments.
	* Cons: Slow, verbose, and error-prone.

**Library Usage**

Lodash is used for the `assignIn` function. Lodash provides a utility function to perform various operations, including object assignment.

**Special JavaScript Features or Syntax**

None mentioned in this benchmark.

**Alternatives**

If you want to explore alternative approaches, consider:

1. **`Object.merge`**: A newer method introduced in ECMAScript 2020, which merges two objects into a new object.
2. **`JSON.mergeObjects`**: A function that merges two JSON-like objects into a new object.
3. **Manual merge using `Object.keys()` and `for...in`**: A traditional approach to merging two objects without relying on built-in methods.

Keep in mind that each alternative has its own pros and cons, which may differ from the options tested in this benchmark.

Related benchmarks:

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

var a = { a: 'oh', b: 'my' }; var b = { c: 'goddess' }; for (const key in b) { a[key] = b[key] }

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

Created: 3 years ago by: Guest

Jump to the latest result

lodash assign

object.assign

spread

For loop

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):