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

Benchmark Definition

The benchmark definition is a JSON object that provides information about the test case. In this case, there are two test cases: "slice" and "substring". The script preparation code and HTML preparation code are empty, which means no additional setup or configuration is required for these tests.

Options being compared

For each test case, we're comparing two different approaches:

1. x.slice(1): This uses the slice() method to extract a subset of characters from the string.
2. x.substring(1): This uses the substring() method to extract a substring from the string.

Pros and Cons

Both methods achieve the same result, but with some differences:

• Performance: In general, slice() is faster than substring(), especially for large strings. However, in this benchmark, there's no noticeable difference.
• String manipulation: slice() allows you to specify a start index and an optional end index. It returns a new string with the specified characters extracted. On the other hand, substring() only takes two arguments: the start and end indices. Both methods return a new string, but they behave slightly differently if the input is not a valid index.
• Browser support: Both methods are widely supported across browsers, but some older browsers might not work with slice() or have quirks when using substring().
• Readability and maintainability: Some developers prefer substring() because it's more explicit about what the method does. Others prefer slice() for its brevity.

Library usage

Neither of these methods uses any external libraries, so there are no libraries to consider here.

Special JavaScript features or syntax

There aren't any special JavaScript features or syntax used in these test cases.

Other alternatives

If you needed to slice a string in JavaScript, before slice() and substring() were introduced, developers could use the following methods:

• String slicing with indexing: You can use array-like indexing (e.g., [start..end]) for substrings. However, this approach is less efficient than using the built-in slice() or substring() methods.
• Using a regular expression: You can use the substr function from the RegExp class to extract a substring. For example: "hello".substr(1) would return "ello".