Benchmark: testing spread versus slice

Tests:

slice
const arr = [ 1, 2, 3 ]; const dup = arr.slice();
spread
const arr = [ 1, 2, 3 ]; const dup = [...arr];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
spread

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 break down the provided benchmark and its results.

**What is being tested?**

The benchmark tests two ways to create a copy of an array in JavaScript: using the `slice()` method and using the spread operator (`...`).

**Options compared**

The options being compared are:

1. **Slice**: Using the `slice()` method to create a shallow copy of an array.
2. **Spread**: Using the spread operator (`...`) to create a new array with the same elements as the original array.

**Pros and Cons**

* **Slice**:
	+ Pros: Fast, efficient, and widely supported across browsers.
	+ Cons: Creates a shallow copy, meaning it only copies the top-level elements of the array. It also creates a new object reference, which may have performance implications if the array contains large amounts of data.
* **Spread**:
	+ Pros: More intuitive syntax for creating new arrays with modified or extended elements. Also, modern browsers support spread syntax natively, making it a more "JavaScript-like" approach.
	+ Cons: May be slower than `slice` due to the overhead of creating a new array and executing the spread operator. Additionally, older browsers may not support spread syntax.

**Library and syntax**

In this benchmark, there is no library being used explicitly mentioned in the code snippets provided. However, the use of modern JavaScript features like spread syntax suggests that the tests are running in an environment where such features are supported.

**Special JS feature or syntax**

The test case uses the spread operator (`...`), which is a modern JavaScript feature introduced in ECMAScript 2015 (ES6). This feature allows creating new arrays with modified or extended elements by duplicating existing arrays using the `...` operator.

**Other alternatives**

While not directly compared in this benchmark, other ways to create copies of arrays in JavaScript include:

1. **Array.prototype.slice.call()**: Creates a shallow copy of an array using the `slice()` method and wrapping it in an array.
2. **Object.assign()**: Copies properties from one or more source objects to a destination object.
3. **JSON.parse(JSON.stringify())**: A more complex approach that uses JSON serialization to create a deep copy of an array.

Keep in mind that these alternatives may have performance implications, depending on the specific use case and browser support.

I hope this explanation helps!

Latest run results:

Run details: (Test run date: 6 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36

Browser/OS: Chrome 69 on Mac OS X 10.13.6

View result in a separate tab

Test name	Executions per second
slice	53064256.0 Ops/sec
spread	24319322.0 Ops/sec

Related benchmarks:

testing spread versus slice (version: 0)

Comparing performance of: slice vs spread

Created: 6 years ago by: Guest

Jump to the latest result

slice

spread

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):