Benchmark: JavaScript create new object with spread operator or Object.assign performance

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);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Using the spread operator
Using Object.assign

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this JavaScript microbenchmark.

The benchmark is designed to compare the performance of two ways to create a new object by combining existing objects: using the spread operator (`...`) and using `Object.assign()`.

**Using the spread operator**

This approach creates a new object by spreading the properties of two existing objects, `firstObject` and `secondObject`, into a new object. The syntax is:
```javascript
const finalObject = { ...firstObject, ...secondObject };
```
The pros of this approach are:

* It's concise and easy to read.
* It avoids the need to explicitly iterate over properties or use `Object.assign()`.

However, some potential cons are:

* It may not be as efficient as other methods, especially for large objects.
* It only works in modern browsers that support the spread operator syntax (ECMAScript 2018+).

**Using Object.assign()**

This approach creates a new object by merging the properties of two existing objects using `Object.assign()`:
```javascript
const finalObject = Object.assign({}, firstObject, secondObject);
```
The pros of this approach are:

* It's widely supported across older browsers and environments.
* It can handle large objects more efficiently than the spread operator.

However, some potential cons are:

* The syntax can be less readable for those not familiar with `Object.assign()`.
* It may require an additional object literal as the first argument to avoid modifying the original objects.

**Library: Lodash**

One of the test cases uses the Lodash library:
```javascript
const _ = require('lodash');
const finalObject = _.merge({}, firstObject, secondObject);
```
Lodash's `_.merge()` function is a utility function that merges two or more objects into a single object. The pros of using Lodash are:

* It provides a concise and readable way to merge objects.
* It handles complex merging scenarios, such as merging arrays.

However, some potential cons are:

* It adds an additional dependency on the Lodash library.
* It may not be necessary for simple object merging tasks.

**Special JavaScript feature: ES6 spread syntax**

This benchmark tests the performance of using the ES6 spread operator syntax (`...`) to create a new object. This is a relatively recent feature in JavaScript, introduced in ECMAScript 2018.

The pros of this approach are:

* It's concise and easy to read.
* It provides better support for large objects and complex merging scenarios.

However, some potential cons are:

* It may not be supported in older browsers or environments that don't implement ES6+ syntax.

**Alternatives**

Other alternatives for creating a new object by combining existing objects include:

* Using `Object.assign()` with an empty object as the first argument (`Object.assign({}, firstObject, secondObject)`).
* Using a library like Lodash (as demonstrated in one of the test cases).
* Manually iterating over properties and using object literals to create a new object.

In conclusion, this benchmark compares the performance of two approaches to creating a new object by combining existing objects: using the spread operator and `Object.assign()`. The choice between these approaches depends on factors such as readability, efficiency, browser support, and additional dependencies.

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:99.0) Gecko/20100101 Firefox/99.0

Browser/OS: Firefox 99 on Windows

View result in a separate tab

Test name	Executions per second
Using the spread operator	5496940.5 Ops/sec
Using Object.assign	6566387.0 Ops/sec

Related benchmarks:

JavaScript create new object with spread operator or Object.assign performance (version: 0)

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

Created: 2 years ago by: Guest

Jump to the latest result

Using the spread operator

Using Object.assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):