- Identify the aspects of your application that vary and separate them from what stays the same.
- Program to an interface, not an implementation. (Program to a supertype)
- Favor composition over inheritance.
- Strive for loosely coupled designs between objects that interact.
- Classes should be open for extension, but closed for modification.
- Depedency Inversion Principle - Depend upon abstractions. Do not depend upon concrete classes.
- Strategy
npm run strategy- The Strategy Pattern defines a family of algorithms, encapsulates each one and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
- Observer
npm run observer- The Observer Pattern defines a one-to-many dependency between objects so that when one object changes state, all of its dependents are notified and updated automatically.
- Decorator
npm run decorator- The Decorator Pattern attaches additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
- Factory Method
npm run factory- The Factory Method Pattern defines an interface for creating an object, but lets subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.
- Abstract Factory
npm run abstract-factory- The Abstract Factory Pattern provides an interface for creating families of realted or dependent objects without specifying their concrete classes.
- Singleton
- The Singleton Pattern ensures a class has only one instance, and provides a global point of access to it.
- Command
npm run command- The Command Pattern encapsulates a request as an object, thereby letting you parmameterize other objects with different requests, queue or log requests, and support undoable operations.
- No variable should hold a reference to a concrete class.
- No class should derive from a concrete class.
- No method should override an implemented method of any of its base classes.