What is design-patterns-js?

This repository is a reference collection of all 23 classic software design patterns from the well known Gang of Four book, each implemented as working JavaScript code using both older prototype style and modern ES6 classes. It is meant as a learning resource rather than a library you install and import into an app, letting you look at real, runnable examples instead of just reading abstract descriptions. The patterns are organized into the three traditional groups. Creational patterns, like Abstract Factory, Builder, Factory Method, Prototype, and Singleton, deal with different ways of creating objects instead of instantiating them directly, giving a program flexibility about what gets created and when. Structural patterns, including Adapter, Bridge, Composite, Decorator, Facade, Flyweight, and Proxy, focus on how classes and objects are composed together to form larger structures or add new behavior without changing existing code. Behavioral patterns, the largest group here with entries like Chain of Responsibility, Command, Iterator, Mediator, Memento, Observer, State, Strategy, Template, and Visitor, are about how objects communicate and coordinate with each other. Each pattern in the repository comes with a short plain English definition pulled from the patterns' original Wikipedia summaries, paired with the actual JavaScript implementation, and a docs.md file is provided so you can browse all the definitions in one place without digging through the code first. The project also includes an automated test suite you can run locally with a standard npm install followed by npm test, which is useful both for verifying the examples work and as further sample code showing how each pattern might be exercised. This project fits developers and students who already write JavaScript and want a concrete, code first way to learn or review design patterns, whether preparing for interviews, teaching a course, or just refreshing their own understanding of these long standing object oriented concepts.