《JavaScript设计模式》笔记二

设计模式的类别

• 创建型设计模式：专注于处理对象创建机制（通过控制创建过程来减少创建对象时导致的项目复杂性）。包括：构造函数、工厂、抽象、原型、单例和生成器。

• 结构型设计模式：关注对象的组合以及确定不同对象之间关系的简单方法（系统的一部分发生变化时，整个结构不受影响；将系统中不适合的部分重铸为符合需求的部分）。包括：装饰器、外观（Facade）、享元（Flyweight）、适配器和代理。

• 行为型设计模式：聚焦于改进或简化不同对象之间的通行。包括：迭代器、中介者、观察者和访问者。

设计模式分类

GoF提及的23种设计模式：

****Creational****	Based on the concept of creating an object.
Class
Factory Method	This makes an instance of several derived classes based on interfaced data or events.
Object
Abstract Factory	Creates an instance of several families of classes without detailing concrete classes.
Builder	Separates object construction from its representation, always creates the same type of object.
Prototype	A fully initialized instance used for copying or cloning.
Singleton	A class with only a single instance with global access points.

****Structural****	Based on the idea of building blocks of objects.
Class
Adapter	Match interfaces of different classes therefore classes can work together despite incompatible interfaces.
Object
Adapter	Match interfaces of different classes therefore classes can work together despite incompatible interfaces.
Bridge	Separates an object's interface from its implementation so the two can vary independently.
Composite	A structure of simple and composite objects which makes the total object more than just the sum of its parts.
Decorator	Dynamically add alternate processing to objects.
Facade	A single class that hides the complexity of an entire subsystem.
Flyweight	A fine-grained instance used for efficient sharing of information that is contained elsewhere.
Proxy	A place holder object representing the true object.

****Behavioral****	Based on the way objects play and work together.
Class
Interpreter	A way to include language elements in an application to match the grammar of the intended language.
Template Method	Creates the shell of an algorithm in a method, then defer the exact steps to a subclass.
Object
Chain of Responsibility	A way of passing a request between a chain of objects to find the object that can handle the request.
Command	Encapsulate a command request as an object to enable, logging and/or queuing of requests, and provides error-handling for unhandled requests.
Iterator	Sequentially access the elements of a collection without knowing the inner workings of the collection.
Mediator	Defines simplified communication between classes to prevent a group of classes from referring explicitly to each other.
Memento	Capture an object's internal state to be able to restore it later.
Observer	A way of notifying change to a number of classes to ensure consistency between the classes.
State	Alter an object's behavior when its state changes.
Strategy	Encapsulates an algorithm inside a class separating the selection from the implementation.
Visitor	Adds a new operation to a class without changing the class.