OOP design pattern example in node js
- Open close: drawShape example (Rectangle and Circle extends Shape)
- Dependency Inversion: High level not depend on low level
- Interface Segregation: robot is a worker but not eating
- Singleton: single DB connection pool, single express object, single data in multi thread
- Factory: create objects of the same base type (multi level base - abstract factory)
- Builder: creator delegate (object)
- Prototype: same as javascript prototype
- Chain of Responsibility: return this in each function (in javascript)
- Object Pool: Limited number of resources (ex: DB connection poll)
- Command: callback, ex Remote with light on command ((new Remote()).setCommand(new LightOnCommand(lightObj)).buttonPressed())
- Observer: redis pub-sub, node event emitter
- Strategy: objects that same method name but difference strategy, delegate, Families of related algorithms (ex change strategy (Agressive, Defensive) of chess or robot before moving)
- Template method: hook, delegate, the methods from subclass are called in the template method from superclass (ex CRUD class in backend cms)
- Adapter: adapter of 3rd libraries (ex topup money, IAP ...)
- Bridge: ex DAO object that implements storage both mysql and mongo (Persistence Frameworks), look and feel in GUI app (GUI frameworks)
- Composition: tree data structure (ex menu as tree, file system as tree ...)
- Decorator: ex DecoratedScrollableWindow, EspressoWithMochaAndWhip
- Flyweight: use when a large number of objects that have some shared state among them (ex game war - solider shared the GraphicalRepresentation, text editor - characters in block has the same style)
- Proxy: The Proxy design pattern is applicable when there is a need to control access to an Object, as well as when there is a need for a sophisticated reference to an Object
- Facade: The Facade Pattern provides a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use. (ex HomeTheaterFacade, Form dialog contains many components)
- Lazy: overwrite method after first execution (in the method scope)
- Nullify: assign variable to null to improve GC
- Try-finally: code in finally block can be executed even after return in try block