Benchmark: JavaScript spread operator vs Object.assign performance v3455676854743

Tests:

Using the spread operator
let firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar', a: 1, b: 2, c: false, d: 'hello' } firstObject = { ...firstObject, ...secondObject };
Using Object.assign
const firstObject = { sampleData: 'Hello world' } const secondObject = { moreData: 'foo bar', a: 1, b: 2, c: false, d: 'hello' } 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

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36 OPR/101.0.0.0

Browser/OS: Opera 101 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Using the spread operator	1064076.9 Ops/sec
Using Object.assign	8564312.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation.

**Benchmark Definition:**

The benchmark measures the performance of two ways to merge objects in JavaScript:

1. Using the spread operator (`...`): This method is used to expand an object into multiple arguments or properties.
2. Using `Object.assign()`: This method is used to copy all enumerable own properties from one or more specified source objects to a destination object.

**Options Compared:**

The benchmark compares the performance of these two methods on a sample dataset. The dataset consists of two objects:

* `firstObject` with a single property `sampleData` containing the string "Hello world".
* `secondObject` with multiple properties (`moreData`, `a`, `b`, `c`, and `d`) containing different data.

**Pros and Cons:**

1. **Using the spread operator (`...`):**
	* Pros:
		+ Concise and readable syntax.
		+ Can be used to merge objects in a more declarative way.
	* Cons:
		+ May incur additional overhead due to function call and argument expansion.
2. **Using `Object.assign()`:**
	* Pros:
		+ More efficient and optimized for performance.
		+ Provides fine-grained control over the merging process.
	* Cons:
		+ Less concise and more verbose syntax.

**Library/Functionality:**

In this benchmark, neither library nor function is explicitly used. However, `Object.assign()` is a built-in JavaScript method that merges objects.

**Special JS Feature/Syntax:**

There are no special JavaScript features or syntax mentioned in the benchmark.

**Other Considerations:**

The benchmark measures the performance of these two methods on a small dataset, which might not be representative of real-world scenarios. The results may vary depending on the size and complexity of the data being merged.

**Alternatives:**

For merging objects, other methods can be used:

* `Object.create()`: Creates a new object with the specified prototype.
* `Object.assign()` alternatives like `lodash.assign()` or `util._merge()`.
* Custom implementation using loops or recursion.

In general, for small datasets and simple merges, the spread operator (`...`) might be sufficient. However, for larger datasets or more complex merges, `Object.assign()` or other methods may provide better performance and control.

Related benchmarks:

JavaScript spread operator vs Object.assign performance v3455676854743 (version: 0)

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

Created: one year 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 2 months ago):