I'll dive into explaining the benchmark.

What is tested:

The provided benchmark tests two approaches for checking if a string ends with a certain substring:

1. endsWith: A method that checks if a string ends with another string using the String.prototype.endsWith() method.
2. slice and triple equal (): An approach that uses the slice() method to extract the last few characters of the string, compares them using triple equals (===) with the target substring.

Options compared:

The benchmark compares the performance of:

1. endsWith
2. slice and triple equal

Pros and Cons:

• endsWith:
  • Pros: Efficient, reliable, and widely supported by browsers.
  • Cons: May be slower for very long strings due to regular expression overhead.
• Slice and triple equal:
  • Pros: Simple, lightweight, and efficient for short substrings.
  • Cons: May lead to issues with edge cases (e.g., null or undefined values), and is not as widely supported by browsers.

Library and purpose:

In this benchmark, the slice() method is used, which is a built-in JavaScript method. The slice() method takes two arguments: the start index and the end index. In this case, the end index is calculated using the length of the target substring (-comparator.length).

Special JS feature or syntax:

There are no special features or syntax used in this benchmark.

Other alternatives:

Alternative approaches for checking if a string ends with another string include:

• Using a regular expression (/endsWith/g): This method is more efficient than endsWith but may be slower for very long strings.
• Using the lastIndexOf() method: This method returns the index of the last occurrence of the target substring, which can be used to determine if the string ends with it.

For example:

function compareLastIndexOf(val, comparator) {
  return val.lastIndexOf(comparator) === val.length - comparator.length;
}

However, these alternatives are not tested in this benchmark.