Why did you have to create separate reverse function? The same could be done in Rot

It could be applied with either functions, but arrow functions always lead to cleaner code. In this solution, the num parameter was changed to length so he can just include the parameter as the length of the array instead of doing this {length: num}. Leads to cleaner code. the underscore at (_, i) basically a placeholder for the value since we don't really need a specific value from an array here.

I'm confused how this works. Can you please explain it to me? Thanks!

Thanks for the explanation

Why that code only work using the structure: "countSheep = length =>"?

JS: for sample tests, values passed to Test.assertSimilar are reversed.

Thanks, cstuncsik!

In javascript this refers to the object you call a function on. But since a function is also an object in javascript you can do this().

Here this refers to the function you call pipe on, so you call the original function with the arguments and pass the result to the piped function as an argument so addOne.pipe(square)(1) is actually square(addOne(1)) where this refers to addOne

Thanks

This was done.