Benchmark: JavaScript spread operator vs Object.assign performance fork

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 28 days ago):

LLMs can make mistakes. Check important info.

Let's dive into explaining what's being tested in this benchmark.

The provided JSON represents a JavaScript microbenchmark that compares the performance of two approaches: using the spread operator (`...`) and `Object.assign` for merging objects.

**What is being tested?**

In this benchmark, we have two test cases:

1. **Using the spread operator**: This approach uses the spread operator (`...`) to merge two objects (`firstObject` and `secondObject`) into a single object (`finalObject`). The syntax looks like this: `{ ...firstObject, ...secondObject }`.
2. **Using Object.assign**: This approach uses the `Object.assign()` method to merge two objects (`firstObject` and `secondObject`) into a single object (`finalObject`). The syntax looks like this: `Object.assign({}, firstObject, secondObject)`.

**Options being compared**

The benchmark is comparing the performance of these two approaches. To understand why, let's consider their implementation:

* **Using the spread operator**: When using the spread operator, JavaScript creates a new object by copying the properties from both objects. This approach has some advantages:
	+ It's more concise and readable.
	+ It avoids modifying the original objects.
	+ However, it can lead to performance issues if the objects are large or have many properties.
* **Using Object.assign**: When using `Object.assign()`, JavaScript creates a new object by copying the properties from both objects. This approach also has its advantages:
	+ It's more efficient than creating a new object with the spread operator, especially for large objects.
	+ However, it can lead to performance issues if the objects are very large or have many properties.
	+ Additionally, `Object.assign()` modifies the original objects.

**Pros and Cons**

Here's a summary of the pros and cons:

* **Using the spread operator**: Pros - more concise, readable, avoids modifying original objects. Cons - can lead to performance issues with large objects.
* **Using Object.assign**: Pros - efficient for large objects, modifies original objects (can be considered a con by some). Cons - less concise, readable.

**Library or special JS feature**

There are no external libraries or special JavaScript features being used in this benchmark. The tests only rely on built-in JavaScript functionality.

**Considerations**

When choosing between these approaches, consider the following:

* If you need to merge objects and performance is a concern, using `Object.assign()` might be a better choice.
* If you prioritize conciseness and readability over performance, using the spread operator (`...`) might be a better fit.

**Other alternatives**

If you're looking for alternative approaches, consider the following:

* **Using Object.create()**: You can use `Object.create()` to merge objects. This approach is similar to `Object.assign()`, but it allows you to specify an existing object as the prototype for the new object.
* **Using a library like Lodash's `_merge` function**: If you need more flexibility in merging objects, you might consider using a library like Lodash, which provides a `_merge()` function that can handle more complex merge scenarios.

I hope this explanation helps you understand what's being tested in this benchmark!

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36

Browser/OS: Chrome 72 on Mac OS X 10.13.6

View result in a separate tab

Test name	Executions per second
Using the spread operator	4239343.5 Ops/sec
Using Object.assign	4317874.5 Ops/sec

Related benchmarks:

JavaScript spread operator vs Object.assign performance fork (version: 0)

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

Created: 5 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 28 days ago):