Node.js has emerged as one of the most popular platforms for building scalable and efficient applications, particularly for backend development.

With its event-driven, non-blocking I/O model, Node.js enables developers to build fast and lightweight applications.

However, as applications grow in size and complexity, developers must adopt structured approaches to maintain code readability, reusability, and scalability.

This is where design patterns come into play.

What are Design Patterns?

Assume you are starting a new farm and, to get produce quickly, you would want to use already tested techniques that will reduce your efforts and deliver the expected output.

If you apply the same approach to your application’s architecture, design patterns provide you with tried-and-tested techniques and a structured approach to solving the problems developers face when designing new systems.

This allows you to create maintainable, robust, and extensible systems.

Following design patterns in the initial stages of an application may take more time, but as the application matures, it will become much easier to maintain and scale when needed.

Adopting design patterns will also improve code readability and promote code reusability.

Types of Design Patterns in Node.js

Node.js development uses different design patterns to handle various situations. Let’s discuss some of the most used design patterns.

1. MVC (Model View Controller)

MVC is one of the oldest design patterns used in object-orientated programming. It divides our application into 3 parts:

• Model

This layer stores or retrieves data from your database; this layer does not perform any business logic on your data and is only responsible for setting up the communication of data between your database and controller in a format they both recognise.

In Node, this will contain our ORMs and the data model defined in it.

• View

This layer directly communicates with the user. This layer is not aware of the business logic that happens in the controller.

This receives data and validates it according to validation constraints, which usually prevent illegal characters and ensure that the data type is correct, then passes it to the next layer.

This would contain the front end of our application.

• Controller

The controller receives requests from View, then validates and processes them according to business logic and updates the model according to the defined logic.

This is the logic you write in your APIs. This layer also receives data from models and sends it to View.

2. MVVM (Model View ViewModel)

This design pattern helps in separating application logic from the user interface and makes it easier for multiple teams to work together.

The design team can primarily focus on the view, while developers focus on business logic, the ViewModel, and the Model.

This design pattern consists of three parts:

• Model

The model defines the application’s business logic and validation rules. The model only communicates with the ViewModel and is unaware of the view.

• View

The view represents the user interface of the application, similar to the MVC design pattern.

• ViewModel

In MVVM, the least amount of code is present in the view, with most of the logic for the view residing in the ViewModel.

The ViewModel acts as a link between the view and the model. It receives and validates UI events from the view, sends them to the model, and updates the view with any changes to the model’s state.

3. MVCS (Model View Controller Service)

MVCS is an extension of the Model View Controller Design pattern; in this pattern, a new Service layer is introduced, which acts between the controller and model.

Here your controller validates and receives requests from View and forwards them to its respective service.

The service layer contains the business logic, and it executes the request and performs the required operation on your data model.

This layer was introduced to prevent overcrowding in the controller layer.

It keeps the controller clean by moving business logic to the service layer, and the controller calls the service layer to perform the respective operations.

This is useful in large-scale projects.

Let’s take an example:

I want to create a new account on the website XYZ.

I fill in all my details in the View Layer, which validates my input and sends it to the controller.

The controller validates the request and ensures that all parameters are correct, & once the validation is completed, it sends the data to the User Service to add a new user.

This service is connected to the user model, which is linked to the database.

When this service receives the command to add a new user, it creates the user from the data and sends it to the model for insertion into the database.

4. Factory Method Design Pattern

The Factory Method Design Pattern simplifies the creation of new objects by providing a generic interface.

This pattern is particularly useful when multiple objects are closely related to each other.

It hides the object creation logic and provides a more flexible way to instantiate objects.

Suppose you are building a woodworking application.

Initially, you learn to create a chair, and you implement the Chair class with all the necessary logic inside it.

Later, if you want to add the functionality to create a table, you would need to create a new Table class with its own implementation.

This would lead to repetitive code across different classes.

The Factory Method Design Pattern suggests that both the Chair and Table classes can derive from a common base class, Woodwork.

In this case, the Chair and Table classes would implement the Woodwork class and define their specific methods, allowing for easier maintenance and scalability while avoiding code duplication.

Conclusion

Design patterns offer developers practical solutions to common problems, improving the efficiency, scalability, and maintainability of their code.

In Node.js, these patterns help manage challenges like asynchronous programming, event-driven architecture, and modularity.

By applying design patterns, you can improve the structure and design of your Node.js apps.

As Node.js evolves, using the right design patterns ensures your applications stay functional while being easy to maintain and scale as your codebase expands.