I'd be happy to help you understand what's being tested in this benchmark.

What is being tested?

MeasureThat.net is testing the performance of two different approaches for calculating the sum of an array: a custom implementation using JavaScript (JS) and an implementation using the Lodash library.

Options compared:

The benchmark is comparing the following options:

1. Custom JavaScript implementation: The code sumJS that uses the forEach method to iterate over the array elements and add them up.
2. Lodash implementation: The code sumLodash that uses the Lodash library's forEach function to iterate over the array elements and add them up.

Pros and cons of each approach:

1. Custom JavaScript implementation:
   • Pros: Simple, easy to understand, and doesn't require any additional libraries.
   • Cons: May be slower due to the overhead of creating a closure and using forEach.
2. Lodash implementation:
   • Pros: Fast, efficient, and optimized for performance.
   • Cons: Requires an external library, which may introduce additional dependencies.

In general, the Lodash implementation is expected to perform better than the custom JavaScript implementation due to its optimized internal logic and caching mechanism.

Library used:

Lodash (version 4.17.5) is a popular JavaScript utility library that provides a wide range of functions for tasks such as array manipulation, string manipulation, and more.

Special JS feature or syntax:

The benchmark uses the forEach method, which is a built-in JavaScript method that allows iterating over an iterable object (such as an array). No special JavaScript features or syntax are required to run this benchmark.

Other alternatives:

If you're interested in exploring other alternatives for calculating the sum of an array, here are a few options:

1. Array.prototype.reduce(): This is another built-in JavaScript method that can be used to calculate the sum of an array.
2. Array.prototype.map() + Array.prototype.reduce(): This approach involves using map() to create a new array with the squared values and then reducing it to calculate the sum.

Keep in mind that these alternatives may have slightly different performance characteristics compared to the custom JavaScript implementation or the Lodash implementation.

I hope this explanation helps!