Let's break down the provided benchmark and explain what's being tested.

Benchmark Definition: The benchmark is defined by two test cases, each with its own script preparation code and HTML preparation code (which is empty in this case). The test cases are designed to measure the performance of JavaScript microbenchmarks.

Test Cases:

1. "to string - replace - and parsed": This test case uses a simple script to:
   • Assign a string value #10 to the variable str.
   • Use the replace() method to remove non-numeric characters (\\D) from the string, resulting in 10.
   • Convert the modified string to a number using parseInt().
   • Assign this new numeric value to strNew.
2. "match": This test case uses a script to:
   • Assign a string value #10 to the variable str.
   • Use the toString() method to convert the string to a string.
   • Use regular expressions (/\\d+/g) to match all occurrences of numeric characters in the string, resulting in an array of numbers [10].
   • Map this array of strings to an array of numbers using map(Number).

Options Compared: The two test cases compare different approaches to achieving a similar result:

1. "to string - replace - and parsed": Uses replace() followed by parseInt(), which is a straightforward approach.
2. "match": Uses regular expressions to match numeric characters in the string, which can be more efficient for larger inputs.

Pros and Cons:

1. "to string - replace - and parsed":
   • Pros: Simple and easy to understand, works well with small inputs.
   • Cons: May not perform well with very large inputs due to repeated string concatenation and parsing.
2. "match":
   • Pros: More efficient for larger inputs, as it only scans the string once and uses a regular expression cache.
   • Cons: Requires knowledge of regular expressions, which can be complex for beginners.

Library/Functions Used:

1. replace(): A built-in JavaScript method used to replace substrings in a string.
2. parseInt(): A built-in JavaScript function used to convert a string to a number.
3. toString(): A built-in JavaScript method used to convert an object to a string.

Special JS Features/Syntax:

None mentioned, but regular expressions are used in the "match" test case. Regular expressions can be complex and may require additional explanation or expertise.

Other Alternatives: There are other ways to achieve similar results, such as:

1. Using RegExp objects instead of regular expressions.
2. Using a library like lodash or underscore for more complex string manipulation tasks.
3. Using a different data structure, like an array or object, to store the numeric values.

Keep in mind that these alternatives may have their own trade-offs and may not be suitable for every use case.