Mastering JavaScript Functional Programming

Thinking recursively

The key to solving problems recursively is assuming that you already have a function that does whatever you need, and just call it normally. (Doesn't this sound weird? Actually, it is quite appropriate: to solve a problem with recursion, you must first solve the problem...) On the other hand, if you try to work out in your head how the recursive calls work and attempt to follow the flow in your mind, you'll probably just get lost. So, what you need to do is:

1. Assume you already have an appropriate function to solve your problem.
2. Then, see how the big problem can be solved by solving one (or more) smaller problems.
3. Solve those problems by using the imagined function from step 1.
4. Decide what are your base cases, simple ...