I'd be happy to explain the benchmark and its different approaches.

Overview of the Benchmark

The benchmark is designed to compare two approaches for removing the last 11 elements from an array in JavaScript: slice() and splice(). The test creates a large array with 1 million elements, pushes 11 more elements into it, and then measures which approach is faster.

Approach 1: Using Array.prototype.slice()

The first benchmark definition uses Array.prototype.slice() to remove the last 11 elements from the array:

list.push(...Array(11))
list = list.slice(-11)

This approach creates a new array slice containing the last 11 elements, and then assigns it back to the original array. The pros of this approach are:

• It is more explicit and readable, as it clearly conveys the intent of removing the last elements.
• It avoids modifying the original array in place.

However, the cons are:

• It creates a new array, which can be memory-intensive for large arrays.
• It may not be the most efficient approach if the array is very large.

Approach 2: Using Array.prototype.splice()

The second benchmark definition uses Array.prototype.splice() to remove the last 11 elements from the array:

list.push(...Array(11))
list = list.splice(-11)

This approach modifies the original array in place, removing the last 11 elements. The pros of this approach are:

• It is more efficient than creating a new array, as it only modifies the existing data.
• It can be faster for large arrays, since it avoids the overhead of creating a new array.

However, the cons are:

• It modifies the original array in place, which may not be desirable if the array needs to remain unchanged.
• The behavior of splice() can be less predictable than slice(), as it modifies the array and returns an array slice.

Library Used: None

There is no library used in this benchmark. Both approaches are built-in methods of the JavaScript Array prototype.

Special JS Feature/ Syntax: None

This benchmark does not use any special JavaScript features or syntax, such as async/await or decorators.

Other Alternatives

If you want to remove the last N elements from an array without using slice() or splice(), there are other alternatives:

• Using Array.prototype.reduce(): You can use reduce() to build a new array with the desired length, like this: list = list.reduce((acc, curr) => acc.length < 11 ? [...acc, curr] : acc.slice(0, -11), []).
• Using Array.prototype.filter(): You can use filter() to create a new array with only the elements you want, like this: list = list.filter((_, i) => i >= 11).
• Using a custom implementation: You can write your own function to remove the last N elements from an array.

Keep in mind that these alternatives may have different performance characteristics than slice() and splice().