Iterator
Provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation. Supports multiple traversals.
Iterator: Walk a Collection Without Its Layout
Sequential access to elements without exposing the underlying structure or its traversal rules.
Iterator in Production: Streams, Paging, and Cursors
Database cursors, API paging, and event streams as iterators.
Advanced Iterator: Internal Iteration and Parallel Traversal
Internal iteration (map/filter), parallel iteration, and iterator adapters.
Iterator: Review & Mastery Quiz
Scenario questions on traversal, paging, and parallelism.
Free Books & Guides
Refactoring.Guru — Iterator
The definitive modern guide to the Iterator pattern. Clear explanations, UML diagrams, real-world analogies, and code examples in multiple languages.
SourceMaking — Iterator
A comprehensive companion guide covering the Iterator pattern with detailed rules of thumb, criticisms, and robust code snippets.
GoF Design Patterns — Iterator
The original Gang of Four book describing the pattern. Available in the "Design Patterns: Elements of Reusable Object-Oriented Software" on Wikipedia.
Official Documentation
Video Courses
freeCodeCamp — Design Patterns Course
A comprehensive multi-hour video course covering all major design patterns with implementations in JavaScript and TypeScript.
Design Patterns in Modern JavaScript Playlist
YouTube playlist covering creational, structural, and behavioral patterns with clear code walkthroughs.
Web Dev Simplified — Iterator
Clear, concise video tutorials covering design patterns with practical examples.
Practice & Examples
Awesome Low-Level Design (GitHub)
A curated collection of free LLD resources, pattern implementations, and interview problems across multiple languages.
Design Patterns Implementation (GitHub)
The most popular open-source collection of design pattern implementations with detailed explanations.
Refactoring.Guru Examples in Iterator
Code examples of the Iterator pattern in TypeScript, Python, Java, and more.