What is being tested?

The benchmark measures the performance of two different approaches to slice an array in JavaScript: using Array.slice() and using the filter() method with a callback function.

Options compared

Two options are being compared:

1. Array.slice(): This method returns a shallow copy of a portion of an array, specified by its start index (inclusive) and end index (exclusive). It is designed to create a new array object containing the elements from the start index up to but not including the end index.
2. Array.filter() with callback function: This method creates a new array with all elements that pass the test implemented by the provided function.

Pros and cons of each approach

1. Array.slice():
   • Pros: Fast, efficient, and predictable performance, as it works with native arrays.
   • Cons: Creates a shallow copy of the original array, which can lead to unexpected behavior if the original array is modified after slicing.
2. Array.filter() with callback function:
   • Pros: More flexible, as it allows for complex filtering conditions using JavaScript functions.
   • Cons: May have slower performance compared to slice(), as it iterates over the entire array and creates a new one.

Library usage

Neither Array.slice() nor Array.filter() uses external libraries. They are native JavaScript methods that work directly with arrays.

Special JS feature or syntax

The benchmark does not use any special JavaScript features or syntax beyond standard ECMAScript 2022 (ES12) support.

Benchmark preparation code

The script preparation code defines an array data and assigns a slice index to create a copy of the last five elements:

var data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];

Individual test cases

The benchmark consists of two individual test cases:

1. slice: Creates a copy of the last five elements using Array.slice().

var copy = data.slice(5);

2. filter: Filters out elements greater than or equal to 5 using Array.filter():

var copy = data.filter(d => d < 5);

Latest benchmark result

The latest benchmark result shows that:

• The Chrome 126 browser on a desktop device executed the slice test case approximately 4.12 million times per second.
• The Chrome 126 browser on a desktop device executed the filter test case approximately 1.39 million times per second.

Other alternatives

If the author wanted to explore other approaches, they could consider:

• Using Array.prototype.map() instead of slice()
• Using a library like Lodash or Ramda for filtering and mapping
• Using a different array manipulation method, such as Array.prototype.slice.call()