Benchmark: Object assignment performance

HTML Preparation code:

<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Tests:

Using the spread operator
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = Object.assign(firstObject, secondObject);
Using lodash.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = _.assign(firstObject, secondObject);
Using for...in
function assign(target, source) { for (let prop in source) { target[prop] = source[prop]; } return target; } const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar' } const finalObject = assign(firstObject, secondObject);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign
Using lodash.assign
Using for...in

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

The provided JSON represents a JavaScript benchmark that tests the performance of different approaches for object assignment.

**Benchmark Definition:**

The benchmark compares the performance of four methods to assign properties from one object to another:

1. **Using the spread operator (`...`)**: This method uses the spread operator to create a new object and then assigns its properties using the `Object.assign()` method.
2. **Using `Object.assign()`**: This method directly calls the `Object.assign()` function to merge two objects.
3. **Using lodash's `assign()` function**: This method uses the `lodash` library's `assign()` function, which is similar to `Object.assign()`.
4. **Using a custom `for...in` loop**: This method manually loops through each property of the source object and assigns it to the target object.

**Options Comparison:**

| Method | Description | Pros | Cons |
| --- | --- | --- | --- |
| Spread Operator (`...`) | Creates a new object with spread properties and then assigns using `Object.assign()`. | Fast, concise, and modern. | May incur extra overhead due to creating a new object. |
| `Object.assign()` | Directly merges two objects using the built-in `assign` function. | Efficient, as it leverages the browser's native implementation. | May have limitations in older browsers or with complex objects. |
| Lodash's `assign()` | Uses lodash's optimized implementation for merging objects. | Fast and reliable, especially for large datasets. | Requires an additional library dependency. |
| Custom `for...in` loop | Manually loops through each property of the source object and assigns it to the target object. | Lightweight, as no extra function calls are made. | Inefficient due to manual looping, which can lead to slower performance. |

**Library Used:**

* **Lodash**: A popular JavaScript library that provides utility functions for various tasks, including array manipulation, string formatting, and object merging.

**Special JS Feature/Syntax:**

The benchmark uses the spread operator (`...`) syntax, which is a modern JavaScript feature introduced in ECMAScript 2018. This feature allows you to create a new object with spread properties and then assign them using the `Object.assign()` method or other methods.

**Other Alternatives:**

For object assignment, there are alternative approaches beyond these four methods:

* Using the `reduce()` function
* Creating an intermediate object and then assigning its properties to the target object
* Using a library like `ramda` or `curio` for functional programming

However, the spread operator, `Object.assign()`, and lodash's `assign()` are among the most common and efficient methods used in JavaScript for object assignment.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.90 Safari/537.36

Browser/OS: Chrome 75 on Linux

View result in a separate tab

Test name	Executions per second
Using the spread operator	3314773.0 Ops/sec
Using Object.assign	3358216.0 Ops/sec
Using lodash.assign	2210454.8 Ops/sec
Using for...in	19957624.0 Ops/sec

Related benchmarks:

Object assignment performance (version: 0)

Comparing performance of: Using the spread operator vs Using Object.assign vs Using lodash.assign vs Using for...in

Created: 5 years ago by: Registered User

Jump to the latest result

Using the spread operator

Using Object.assign

Using lodash.assign

Using for...in

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):