Benchmark: 4-tuple array slice vs spread operator

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

const arr = [1, 2, 3, 4]

Tests:

slice
arr.slice(0, 3)
spread operator
[arr]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
spread operator

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/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
slice	52785092.0 Ops/sec
spread operator	185136928.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark you provided tests the performance of two different methods of creating a new array from an existing array, specifically using a slice of an array and using the spread operator. Here's a breakdown of the specifics of the benchmark, the comparisons being made, the pros and cons of each method, and other considerations for developers.

### Benchmark Overview

**1. Methods Tested:**
   - **Array.prototype.slice**: `arr.slice(0, 3)` creates a shallow copy of a portion of the original array, starting from index 0 up to, but not including, index 3.
   - **Spread Operator**: `[arr]` attempts to create a new array from the existing array `arr`. However, it should be noted that the correct usage for getting a copy of the portion of the array using the spread operator would typically be `[...arr.slice(0, 3)]` or simply `arr.slice(0, 3)` for clarity. In this benchmark, the intention seems to be focused on a comparison, but the syntax used for the spread might not perform the intended operation correctly.

**2. Results Overview:**
   - The benchmark shows that in terms of executions per second, the spread operator method significantly outperforms the slice method, with 185,136,928 vs. 52,785,092 executions per second. This indicates that the spread operator is more efficient in this particular implementation.

### Pros and Cons of Each Approach

#### Array.prototype.slice
- **Pros:**
  - The method is widely understood among developers familiar with JavaScript's array manipulation methods.
  - It allows specific index ranges to be defined clearly, thus providing control over the subset of the array being copied.

- **Cons:**
  - It may be slower compared to other methods, especially for larger arrays, as observed in the benchmark.
  - For simple copying of the entire array, developers would need to specify start and end indices unnecessarily.

#### Spread Operator
- **Pros:**
  - The syntax is concise and can be more readable for copying elements from an array.
  - The spread operator can handle varying numbers of elements easily and expands arrays in a flexible manner.

- **Cons:**
  - Incorrect usage (as noted in this benchmark) could lead to confusion or unexpected results. 
  - It requires ES6 support; thus, in older environments that don't support it, alternative methods like `slice` would be necessary.

### Other Considerations
- **Performance**: The benchmark results illustrate that while the spread operator is faster in this instance, performance can vary based on the size of arrays and the JavaScript engine. Developers should profile performance in the context of their application.
- **Readability and Maintainability**: Developers should balance performance with readability and maintainability. For instance, using methods that are more widely understood may benefit teams that have varying degrees of experience.

### Alternatives
- **Array.from()**: This method can create a new array from an existing one and provides more options, such as mapping as part of the process. It's very readable and flexible for creating arrays from iterable objects.
  
- **Array.prototype.concat**: While typically used for merging arrays, it can also be used to copy portions of an array. This method could be more verbose but is flexible in handling array structures.

In conclusion, both array slicing and the spread operator have viable use cases and trade-offs. Understanding the environment and the specific needs of the application will guide developers in choosing the most appropriate method.

Related benchmarks:

4-tuple array slice vs spread operator (version: 1)

Comparing performance of: slice vs spread operator

Created: one year ago by: Guest

Jump to the latest result

slice

spread operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):