JavaScript: Functional Programming for JavaScript Developers

Iterator

Traversing collections of objects is an amazingly common problem. So much so that many languages provide for special constructs just for moving through collections. For example C# has a foreach loop and Python has for x in. These looping constructs are frequently built on top of an iterator. An iterator is a pattern that provides a simple method for selecting, sequentially, the next item in a collection.

The interface for an iterator looks like this:

interface Iterator{
  next();
}

Implementation

In the land of Westeros there is a well-known sequence of people in line for the throne in the very unlikely event that the king was to die. We can set up a handy iterator over the top of this collection and simply call next on it should the ruler ...