Node.js is a widely used JavaScript engine that provides an event-driven, non-blocking I/O mechanism for creating scalable network applications. Node.js applications, like those written in any other modern framework, can improve in terms of code reuse, maintainability, and resilience by following established design patterns. In this piece, we'll take a look at some of the best design patterns that may be applied to Node.js.

What are Design patterns?

Design patterns are reusable solutions to recurrent challenges that software professionals face during the course of their coding careers. They support the use of the most effective strategies in software architecture while also offering an organized approach to problem solving. Developers are able to create codebases that are more robust, manageable, and extensible when they make use of design patterns.

The paradigm of object-oriented programming (OOP) is particularly well suited to the implementation of all patterns. However, due to the adaptability of JavaScript, similar ideas can also be implemented in programs that do not use object-oriented programming.

The importance of Design patterns in Node.js

In the realm of software design, the non-blocking event-driven architecture that Node.js is famous for presents a unique set of difficulties and opportunities. Implementing design patterns that are specific to Node.js can potentially result in apps that are more streamlined and efficient.

It is crucial that we use tried-and-true recommendations that can help us design efficient and resilient code when developing Node.js applications. Design patterns are a set of commonly used conventions. Design patterns are a tried-and-true method of resolving software development issues.

Let's have a look at some of the most important design patterns in the Node.js world:

  • Immediately invoked function expressions (IIFE)

The simultaneous function definition and invocation pattern is the first one we'll look at. Due to the nature of JavaScript scopes, IIFEs can be used effectively to imitate features like class private properties. In fact, this pattern is sometimes included in the stipulations of others that are more involved.

  • Singleton pattern

Another tried-and-true design pattern is the singleton. It's a basic pattern, but it's useful for counting how many times a class is instantiated. The pattern ensures that you never have more than one.

With the singleton pattern, there is always one instance of a class available for use, and it may be accessed from anywhere. The singleton paradigm is useful for managing resources in Node.js because modules may be cached and shared across the application. It is possible to implement a database connection pool as a singleton in order to save resources.

  • Factory pattern

The factory pattern provides an option for the creation of objects that does not require the developer to identify the particular class of object that will be produced. When working with asynchronous tasks like reading files or performing API calls, for example, this can make the process of object creation in Node.js much simpler. The factory pattern improves both the readability and the reusability of code since it abstracts the process of creating objects.

You are able to concentrate the logic involved in the process of creating objects (such as which object to build and why) in a single location by using the factory method. Because of this, you are free to concentrate on merely seeking the object you require and then making use of it.

  • Observer pattern

The observer pattern works exceptionally well with the event-driven nature of Node.js. A subject that follows this pattern is responsible for keeping a list of its dependents, also known as observers, and notifying them whenever there is a change in the state. This is something that may be utilized within the framework of Node.js to construct event-driven systems, such as real-time applications and chat applications.

The observer pattern enables you to react to a given input rather than actively verifying its presence. In other words, this pattern allows you to wait passively for a certain type of input before proceeding with your code. It can be done once and forgotten about.

  • Middleware patterns

The middleware architecture provided by Node.js is frequently utilized in web applications for the purpose of managing requests and responses. The middleware pattern consists of a series of functions that carry out the processing of a request in the order listed. Before sending it on to the next function in the chain, each function in the chain has the ability to make changes to either the request or the response. This approach improves modularity and makes it possible for developers to plug in a wide variety of capabilities while keeping them loosely coupled.

The request, the response, and the next parameters are the inputs to the middleware functions. Implementing the chain of responsibility is aided by designating the HTTP request object as the "request," the HTTP response object as the "response," and the next middleware function as the "next" parameter to the function calling it.

Authentication, logging, and error handling are just some of the many uses for middleware design patterns. It's a potent instrument for creating Node.js apps that are modular, scalable, and easy to maintain.

  • Module pattern

In Node.js, the module pattern is considered to be one of the most fundamental but fundamentally basic patterns. It gives you the ability to divide your code into different files or modules that each have a specialized set of functionalities.

This design encapsulates data and exposes only a public application programming interface (API). The module pattern is widely used in Node.js for the purpose of organizing code into modules that are both reusable and portable.

Middleware modules, utility libraries, data access layers, and other such things are a few more examples. The pattern makes it easier to handle dependencies and conceals implementation specifics.

  • Decorator pattern

Decorators are able to dynamically add additional functionality to objects without having that functionality affect other instances of the object. This is an excellent method for extending Node's basic modules.

It's a classy approach to adding to an object's capabilities. This pattern is employed to dynamically augment or even alter an object's behavior at runtime. Although the result may be reminiscent of class inheritance, this approach permits switching between behaviors within the same execution, whereas inheritance does not.

The purpose of this pattern is to add additional features to an object by wrapping them in their own methods or classes. That way, you can add new ones with little effort or modify old ones without rewriting any code that relies on them.

  • Dependency injection pattern

Dependency injection is a design strategy in Node.js that helps separate different parts of an application so they can be independently tested and maintained. Modules and classes can make use of dependency injection to avoid having to create dependencies on their own. It's useful for reusability, testability, and decoupling.

Delegating the generation and maintenance of an object's dependencies (i.e., the other objects it needs in order to function) to a separate component is the core principle underlying dependency injection. At runtime, an object obtains its dependencies from somewhere other than the object itself.

  • Command pattern

This handy tool enables you to hide complicated functionality behind a single module (or class, if you want), which can then be accessed from the outside using a relatively straightforward application programming interface (API).

Because the business logic is broken up into its own distinct command classes, each of which uses the same application programming interface (API), the primary advantage of this design is that it enables you to do things like add new ones or update the current ones with minimal influence on the rest of your project.

  • Adapter pattern

Another design that is deceptively straightforward yet incredibly effective is the adapter pattern. In its most basic form, it facilitates the transformation of one application programming interface (API) into another. By "API," I mean the collection of methods that a specific object possesses.

To clarify, what I mean is that the adapter is essentially a wrapper around a specific class or object. This wrapper offers a different API but still makes use of the object's original API in the background.

  • Prototype pattern

In the context of the node, a prototype design pattern is categorized as a creational design pattern. This classification indicates that the prototype design pattern enables us to build new objects that are based on objects that already exist. The basic idea behind this design pattern is to start by making an object that will serve as a prototype, and then to make a new item by cloning the prototype.

When developing many objects that have the same set of attributes and operations, this technique proves invaluable. The prototype design pattern is commonly used in a Node.js environment to build objects and implement inheritance. Prototype design patterns allow us to cut down on unnecessary lines of code, which in turn boosts our app's efficiency.

  • Builder pattern

The goal of this pattern is to enable developers to work independently on both the implementation and the representation of complicated objects. The pattern in the Node.js builder is a method for constructing complicated objects in a sequential fashion.

Builder design patterns are commonly used by experienced programmers when there are several methods for creating an object or a large number of properties within the object. The builder design pattern simplifies the process of making long-term changes to large code by dividing it into smaller, more manageable chunks.

The developer's ability to lay out the object's structure in advance is key to the builder pattern. Then, while instantiating the object, the programmer can make copies with varying settings.

  • The chain of responsibility pattern

You can achieve this by separating the requester from the object that responds to it in your code. In other words, there could be three distinct objects (R1, R2, and R3) that all get the same request (R) from object A. Which one should A send R to, and how can it tell? Does A need to worry about that?

To address your final query, the correct response is “no”. If A doesn't need to know who's handling the request, then why not let R1, R2, and R3 choose among themselves?

This is where the concept of "chain of responsibility" comes into play; we are setting up a series of objects to receive requests and then attempt to complete them or pass them along if they are unable to.

  • Streams

Streams in Node.js allow for the efficient processing of big data sets by splitting them up into smaller pieces. However, developers are often forced to process data in streams by constructing pipelines of streams so that all of the data may be handled in a stage-by-stage fashion; when they do so, they are employing the chain of responsibility approach.

Let's take this into account. Let's pretend we need to take some information from a file, edit it, and then save the results to another file. The data can be read from the file at the "read stream," transformed at the "transform stream," and written to a new file at the "write stream" to accomplish the aforementioned tasks.

Implementing Design patterns


1. Understanding context

The context of your application must be understood before you can effectively use any design pattern. Think about things like the app's prerequisites, your scalability requirements, and the problems you're trying to solve. It is important to modify design patterns so that they work with your specific project requirements.

2. Modularization

Node.js's module structure promotes modularity. Maintaining small, narrowly scoped modules with a single job is essential when using design patterns. This facilitates code reusability and maintainability by making it less of a hassle to switch out or improve individual features without having to redo the whole thing.

3. Asynchronous patterns

Due to the asynchronous nature of Node.js, it is crucial to select design patterns that are compatible with such frameworks. The observer pattern and the middleware pattern are examples of asynchronous design patterns that developers can use to easily manage events and asynchronous tasks.


Node.js programmers can write code that is easier to read, more versatile, and more secure with the assistance of design patterns. You may construct large-scale systems that are simple to keep up-to-date and expand by utilizing patterns that have been proven successful in the past, such as factories, decorators, and singletons. In order to achieve mastery in advanced Node programming, one must have an in-depth acquaintance with the application of design concepts.

A design pattern is a reusable solution to a recurring problem in software engineering that is implemented to increase both code quality and efficiency. The documentation and discussion of design-level problem-solving techniques are typically done using design patterns.