Benchmark: 2x slice, 2x spread vs filter

Script Preparation code:

var arr = ['a', 'b', 'c', 'd',];

Tests:

1
console.log([...arr.slice(0, 1), ...arr.slice(2)]);
2
console.log(arr.filter((_, i) => i !== 1));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
1
2

Fastest: N/A

Slowest: N/A

Latest run results:

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

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**Benchmark Definition**

The benchmark definition is represented by two JSON objects: `Name` and `Script Preparation Code`. The name of this benchmark is "2x slice, 2x spread vs filter". This means that the benchmark compares the performance of three different approaches to achieve a similar result:

1. Using `slice(0, 1)` followed by spreading the resulting array using the spread operator (`...`).
2. Using `filter((_, i) => i !== 1)` to create a new array with all elements except the second one.
3. A combination of both approaches (see individual test cases below).

**Script Preparation Code**

The script preparation code is provided in JavaScript and creates an array `arr` containing five string elements: `'a'`, `'b'`, `'c'`, `'d'`.

**Individual Test Cases**

There are two test cases:

1. **Test Case 1**
```javascript
console.log([...arr.slice(0, 1), ...arr.slice(2)]);
```
This test case measures the performance of spreading an array created by taking the first and last elements using `slice()`. The resulting array will contain `'a'` and `'d'`.

Pros: This approach is concise and easy to read.

Cons: It creates two intermediate arrays, which can lead to higher memory usage and potentially slower execution.

2. **Test Case 2**
```javascript
arr.filter((_, i) => i !== 1);
```
This test case measures the performance of using `filter()` to create a new array with all elements except the second one (`i !== 1`).

Pros: This approach is more memory-efficient since it avoids creating intermediate arrays.

Cons: It may be less concise and harder to read due to the use of a callback function.

**Latest Benchmark Result**

The latest benchmark result shows that Test Case 2 (using `filter()`) outperforms Test Case 1 (spreading an array) in terms of executions per second, with a difference of approximately 32%. This suggests that using `filter()` is the most efficient approach for this specific use case.

**Library: filter()**

The `filter()` function is a built-in JavaScript method that creates a new array by filtering elements based on a provided callback function. In this benchmark, the callback function simply checks if the index `i` is not equal to 1 (`i !== 1`). The purpose of using `filter()` here is to remove the second element from the original array.

**Other Alternatives**

While not explicitly mentioned in the benchmark definition, alternative approaches could include:

* Using `map()` with a callback function that returns an empty string for the second element
* Creating a new array by concatenating two arrays (e.g., using `[...arr.slice(0, 1), ...[]].concat(arr.slice(2))`)
* Using a loop to iterate over the elements and skip the second one

Keep in mind that these alternative approaches might have different performance characteristics and trade-offs compared to the `filter()` method used in this benchmark.

Related benchmarks:

2x slice, 2x spread vs filter (version: 0)

Comparing performance of: 1 vs 2

Created: 3 years ago by: Registered User

Jump to the latest result

1

2

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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