Benchmark: Shallow Copy Array - Slice vs Spread vs Filter

Tests:

Slice
array = [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5]; arrayCopy = array.slice();
Spread
array = [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5]; arrayCopy = [...array];
Filter
array = [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5]; arrayCopy = array.filter(() => true);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Slice
Spread
Filter

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Windows

View result in a separate tab

Test name	Executions per second
Slice	3982710.5 Ops/sec
Spread	3902864.2 Ops/sec
Filter	3220043.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explore what is being tested, the options compared, pros and cons of each approach, and other considerations.

**Benchmark Definition**

The benchmark is designed to test three different approaches for creating a shallow copy of an array: using `slice()`, `spread` operator (`...`), and `filter()`.

**Options Compared**

1. **Slice**: Creates a new array by extracting a portion of the original array using the `slice()` method.
2. **Spread Operator**: Creates a new array by spreading the elements of the original array into a new array using the spread operator (`...`).
3. **Filter**: Creates an empty array by filtering out all elements from the original array, returning only true values (which are considered as empty values).

**Pros and Cons of Each Approach**

1. **Slice**
	* Pros: Fast and efficient way to create a shallow copy of an array.
	* Cons: Can be brittle if the number of elements is large, as it creates a new array with references to the original elements.
2. **Spread Operator**
	* Pros: Creates a new array without modifying the original, which can be safer for very large arrays.
	* Cons: Requires JavaScript 2015+ syntax, and may not be as performant as `slice()` on smaller arrays.
3. **Filter**
	* Pros: Can create an empty array with no overhead if all elements need to be filtered out.
	* Cons: May be slower than `slice()` or spread operator for most use cases.

**Library/Function Usage**

None of the test cases uses any external libraries or functions beyond the standard JavaScript `Array` methods. The tests rely on built-in JavaScript features and APIs.

**Special JS Features/Syntax**

The benchmark does not explicitly test any special JavaScript features or syntax, such as async/await, ES6 classes, or modern ECMAScript modules. It only uses standard JavaScript features for array manipulation and comparison.

**Other Considerations**

1. **Array Length**: The original array has 40 elements, which may affect the performance differences between the approaches.
2. **Browser Variability**: The benchmark results are from Chrome 120 on a Windows desktop, which might not be representative of other browsers or platforms.
3. **Execution Frequency**: The number of executions per second (e.g., 3982710.5 for the "Slice" test) can impact performance differences between the approaches.

**Alternatives**

Other approaches to create shallow copies of arrays in JavaScript include:

1. `Array.prototype.concat()`: Creates a new array by concatenating multiple arrays.
2. `Object.assign()`: Creates a new object by copying properties from an existing object.
3. `Array.prototype.map()` or `Array.prototype.forEach()`: Can be used to create new arrays with transformed data.

These alternatives may have their own trade-offs and performance characteristics, depending on the specific use case and requirements.

Related benchmarks:

Shallow Copy Array - Slice vs Spread vs Filter (version: 0)

Comparing performance of: Slice vs Spread vs Filter

Created: 2 years ago by: Guest

Jump to the latest result

Slice

Spread

Filter

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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