Benchmark: Slice vs splice (copy)

Script Preparation code:

var arrayOne = [1, 3, 5, 11, 13];
var index = arrayOne.indexOf(5);

Tests:

Splice
const arr = [...arrayOne]; arr.splice(index, 1);
Slice
[...arrayOne.slice(0, index), ...arrayOne.slice(index+1) ]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Splice
Slice

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its test cases.

**Benchmark Overview**

The benchmark is designed to compare two approaches for copying an array slice: using `splice()` with a copy (Splice) versus creating a new array using spread syntax (Slice). The goal is to determine which approach is faster in JavaScript.

**Script Preparation Code**

Before running the tests, the script preparation code creates an array `arrayOne` and finds its index at position 4, where the value 5 resides. This array will be used as the source for both test cases.

```javascript
var arrayOne = [1, 3, 5, 11, 13];
var index = arrayOne.indexOf(5);
```

**Test Cases**

There are two test cases:

1. **Splice**: The benchmark uses `splice()` to create a copy of the slice. Specifically:
   ```javascript
const arr = [...arrayOne]; // Create an array with a copy of the original array's elements
arr.splice(index, 1); // Remove one element from the copied array
```
   This approach is known as "in-place" because it modifies the original array.
2. **Slice**: The benchmark creates a new array using spread syntax to create a copy of the slice:
   ```javascript
[...arrayOne.slice(0, index), ...arrayOne.slice(index+1)] // Create an array with the desired elements copied
```
   This approach is known as "out-of-place" because it creates a new array without modifying the original.

**Pros and Cons**

- **Splice (In-place)**:
  - Pros: More intuitive, uses less memory.
  - Cons: Can be slower for large arrays since it modifies the original array.
- **Slice (Out-of-place)**:
  - Pros: Faster, more efficient for large arrays since it doesn't modify the original array.
  - Cons: Requires creating an extra array, can use more memory.

**Library and Special JS Features**

There are no libraries used in this benchmark. However, note that JavaScript provides a `Date` object to handle timing and execution statistics, which is utilized here through `new Date().getTime()`.

**Other Alternatives**

1. **Array.prototype.map()**: Another way to create an array copy would be using `map()`:
   ```javascript
const arr = arrayOne.slice(0, index).map(() => 5);
```
   This approach would also require creating a new array and doesn't directly compare with the `splice()` or spread syntax approaches.

2. **Array.prototype.reduce()**: Creating an array copy using `reduce()`:
   ```javascript
const arr = [arrayOne.slice(0, index), arrayOne.slice(index+1)].reduce((a, b) => [...a, ...b]);
```
   Similar to `map()`, this would create a new array and doesn't directly compare with the `splice()` or spread syntax approaches.

3. **Other in-place techniques**: There are other in-place methods like `concat()`, but using them for creating an array copy would not align well with the benchmark's goal of comparing performance between different copying methods.

Each alternative provides a way to create an array copy, but they differ significantly from the direct comparisons offered by `splice()` and spread syntax.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:79.0) Gecko/20100101 Firefox/79.0

Browser/OS: Firefox 79 on Ubuntu

View result in a separate tab

Test name	Executions per second
Splice	4829600.0 Ops/sec
Slice	4667117.5 Ops/sec

Related benchmarks:

Slice vs splice (copy) (version: 0)

Comparing performance of: Splice vs Slice

Created: 4 years ago by: Guest

Jump to the latest result

Splice

Slice

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):