Mastering JavaScript Design Patterns - Second Edition

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 ...