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

@user2686621 If you google "change of base," there are two good resources - purplemath and khan academy. Each has a helpful explanation of what's going on here. As for the logarithm itself, there is no "physics" meaning. Instead, think of it as a mathematical construction where log(x) means "the exponent of 10 (or whatever the 'base' of the logarithm is - e in this case) that gives me x." Not sure if this helps, but hope so.

I think setting rebounds to -1 initially takes care of the "last bounce" problem.

Not sure what you mean by asynchronous code, but this solution definitely slows down considerably as the list lengthens. And yes, using a for loop that returns as soon as it finds its target, you'll return the answer more or less instantly if that target is near the beginning, even on lists millions of ints long. Not so for this 'top' solution.

This isn't async code, this is functional programing.