Benchmark: lodash merge vs object.assign vs spread with empty object

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

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

LLMs can make mistakes. Check important info.

**Overview**

The provided JSON represents a JavaScript microbenchmark on the website MeasureThat.net, which compares the performance of three different approaches: `_.merge` from the Lodash library, `Object.assign()`, and the spread operator (`{ ...a, ...b }`). The benchmark is designed to test how these functions merge two objects, with one object being empty (`{}`) and the other containing a single key-value pair (`{ c: 'goddess' }`).

**Approaches Compared**

The three approaches are compared in terms of their performance:

1. **_.merge()`**: This function is part of the Lodash library and is used to merge two objects recursively.
2. **Object.assign()**: This method is built-in to JavaScript and returns a new object with properties from multiple sources (arrays, objects).
3. **Spread operator (`{ ...a, ...b }`)**: This operator creates a new object by copying all enumerable own properties from one or more source objects.

**Pros and Cons of Each Approach**

1. **_.merge()**:
	* Pros: It recursively merges nested objects, making it suitable for complex data structures.
	* Cons: It has a higher overhead due to its recursive nature, which can impact performance in simple cases.
2. **Object.assign()**:
	* Pros: It is lightweight and efficient, as it only copies enumerable properties from the source objects.
	* Cons: It assumes that the source objects are arrays or objects with enumerable properties, which may not be the case for all inputs.
3. **Spread operator (`{ ...a, ...b }`)**:
	* Pros: It is concise and expressive, making it suitable for simple merge operations.
	* Cons: It has a higher overhead due to object creation and property iteration, which can impact performance in large datasets.

**Library Used**

The `_.merge()` function from Lodash is used in the benchmark. Lodash is a popular utility library that provides a set of functional programming helpers, including data manipulation functions like `_.merge()`. It is widely used for its concise and expressive way of solving common JavaScript problems.

**Special JS Features/Syntax**

None are explicitly mentioned in the provided code or benchmark results.

**Alternatives**

If you're looking for alternatives to these approaches, here are a few options:

1. **Use the `Object.assign()` method with `Array.prototype.concat()`**: This can be used as an alternative to the spread operator.
```javascript
const c = Object.assign({}, a, Array.prototype.concat(b)[0]);
```
2. **Use a custom merge function**: You can create a custom function that iterates over the properties of both objects and creates a new object with the merged values.
```javascript
function mergeObjects(a, b) {
  const result = {};
  for (const key in a) {
    if (Object.prototype.hasOwnProperty.call(b, key)) {
      result[key] = mergeObjects(a[key], b[key]);
    } else {
      result[key] = a[key];
    }
  }
  return result;
}
```
3. **Use a library like Immutable.js**: This library provides an immutable data structure that can be used to merge objects in a predictable and efficient way.

Keep in mind that the choice of approach depends on the specific requirements of your project, including performance, conciseness, and complexity handling.

Latest run results:

Run details: (Test run date: 5 months 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	2705456.5 Ops/sec
object.assign	4890721.5 Ops/sec
spread	12668117.0 Ops/sec

Related benchmarks:

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

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

Created: 5 months 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 one month ago):