I'd be happy to explain what's being tested in the provided JSON benchmark.

What is being tested?

The benchmark compares two ways of executing arithmetic expressions: using the eval() function and creating a new anonymous function using the Function() constructor.

Options compared:

1. eval(): This method executes a string as JavaScript code, allowing you to execute arbitrary expressions.
2. Function() constructor: This method creates a new, unnamed function that can be executed like any other function. The expression is passed as an argument to the constructor.

Pros and Cons of each approach:

1. eval():
   • Pros: Very concise and easy to use for simple expressions.
   • Cons:
     • Security risks due to the ability to execute arbitrary code.
     • Performance overhead compared to direct arithmetic execution.
2. Function() constructor:
   • Pros:
     • More secure than eval() since it doesn't execute arbitrary code.
     • Can be faster for simple expressions, as it avoids the overhead of parsing and executing JavaScript syntax.
   • Cons: Requires more code to achieve the same result.

Library usage:

There is no explicit library being used in this benchmark. However, if you were to use a library like es5-shim or browserlist, you might use it to enable the Function() constructor or polyfill other features required by modern browsers.

Special JS feature or syntax:

This benchmark doesn't use any special JavaScript features or syntax beyond what's commonly used in everyday development. However, if you wanted to test a more advanced feature like Arrow functions (introduced in ECMAScript 2015), it might look like this:

const new_function = () => 4 * 6;
new_function();

Other alternatives:

For testing arithmetic expressions, other approaches could include:

1. Using Mathematical expression parser libraries like express-eval or mathjs.
2. Creating a custom arithmetic expression evaluator using a stack-based approach.
3. Testing the execution of arithmetic expressions in different JavaScript engines (e.g., SpiderMonkey, V8) using benchmarking frameworks like node-benchmark.

Keep in mind that these alternatives might not be as straightforward to implement and may require more expertise in JavaScript implementation details.

Let me know if you'd like me to elaborate on any of these points or provide further insights!