Mastering JavaScript Functional Programming - Second Edition

Traversing a tree structure

Data structures, which include recursion in their definition, are naturally appropriate for recursive techniques. Let's consider, for example, how to traverse a complete filesystem directory, listing all of its contents. Where's the recursion? The answer is clear 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 that when we encounter a directory, we also list its contents, and if those include more directories, we also list them, and so on. We'll be using the same node functions as in getDir() (from the ...