Mastering JavaScript Functional Programming

Traversing a tree structure

Data structures, which include recursion in their definition, are naturally appropriate for recursive techniques. Let's consider here, for example, how to traverse a complete file system directory, listing all of its contents. Where's the recursion? The answer follows if you consider that each directory can do either of the following:

• Be empty -- a base case, in which there's nothing to do
• Include one or more entries, each of which is either a file or a directory itself

Let's work out a full recursive directory listing -- meaning, when we encounter a directory, we proceed to also list its contents and, if those include more directories, we also list them, and so on. We'll be using the same Node.js functions as ...