Design patterns are general solutions to common problems in software design. They are like pre-made templates that programmers can follow to solve common problems in their code. By using design patterns, you can make your code more flexible, reusable, and understandable. In the context of NodeJS, there are several design patterns that can be useful. In this chapter, we'll explore some of the most important ones.
Factory Default
The Factory pattern is a creation pattern that provides an interface for creating objects in a superclass, but allows subclasses to change the type of objects that will be created. In NodeJS, you can use this pattern when you need a flexible and extensible way to create objects. For example, if you are creating an API that can return different types of responses based on input parameters, you can use the Factory pattern to create different types of response objects.
Singleton Pattern
The Singleton pattern ensures that a class has only one instance and provides a global access point to it. In NodeJS, this pattern can be useful for things like database connections, where you might want to limit the number of connections open at the same time. By using the Singleton pattern, you can ensure that only one database connection is created and that connection is reused throughout your application.
Observer pattern
The Observer pattern is a behavior pattern that allows an object (the "subject") to keep a list of its dependents (the "observers") and automatically notify them of any state changes. In NodeJS, you can use this pattern to create events and event listeners. For example, you might have an object that emits an event whenever a record is added to a database, and other objects that listen for that event and respond to it in some way.
Middleware Standard
The Middleware pattern is a type of structural design pattern that allows you to perform an action before or after a main operation. In NodeJS, this pattern is commonly used in web frameworks like Express.js, where you can use middleware to perform actions like user authentication or logging before the main operation (like serving a web page) is performed.
Module pattern
The Module pattern is a framework pattern that lets you organize your code into self-contained, reusable modules. In NodeJS, this pattern is fundamental, as it allows you to organize your code in a modular and reusable way. Every module in NodeJS has its own scope, so the variables, functions and objects you define in a module are not visible to other modules unless you decide to export them.
These are just some of the design patterns you can use when building APIs in NodeJS. Each of these patterns has its own advantages and disadvantages, and which one to use depends very much on the specific problem you are trying to solve. However, by understanding these patterns and knowing when and how to use them, you can make your code cleaner, easier to understand, and easier to maintain.
In addition to these design patterns, there are many other patterns you can use in NodeJS, including the Prototype pattern, the Decorator pattern, the Strategy pattern, and many others. By learning and using these patterns, you can become a more effective and efficient NodeJS developer.
