What is being tested?

The provided benchmark tests the performance of three different approaches for concatenating strings in JavaScript:

1. Using the + operator (also known as the "string concatenation" or "plus operator")
2. Using the concat() function
3. Using template literals (${})

Options comparison:

Here's a brief overview of each approach, their pros and cons, and some considerations:

1. Using the + operator:
   • Pros: Simple, widely supported, and efficient.
   • Cons: Can be less readable than other approaches, especially for complex concatenations.
   • Considerations: This method is often used in JavaScript code, but it can lead to a lot of unnecessary string allocations and copying, which can impact performance.
2. Using the concat() function:
   • Pros: More readable than using the + operator, as it explicitly separates concatenation from other operations.
   • Cons: Less efficient than using template literals or the + operator.
   • Considerations: The concat() function is a built-in method that creates a new string object each time it's called. This can lead to unnecessary allocations and copying.
3. Using template literals (${}):
   • Pros: Most readable of the three options, as it explicitly separates variables from formatting.
   • Cons: Requires support for ES6+ syntax ( template literals were introduced in ECMAScript 2015).
   • Considerations: Template literals are a concise way to format strings and can be more efficient than using concat() or the + operator.

Libraries used in test cases:

None of the provided benchmark definitions include any external libraries. However, it's worth noting that some JavaScript engines may use internal libraries for string manipulation.

Special JS features or syntax:

The benchmark uses ES6+ syntax (template literals) and assumes support for let and const declarations, which were introduced in ECMAScript 2015.