Book Image

Node.js Design Patterns - Third Edition

By : Mario Casciaro, Luciano Mammino
5 (1)
Book Image

Node.js Design Patterns - Third Edition

5 (1)
By: Mario Casciaro, Luciano Mammino

Overview of this book

In this book, we will show you how to implement a series of best practices and design patterns to help you create efficient and robust Node.js applications with ease. We kick off by exploring the basics of Node.js, analyzing its asynchronous event driven architecture and its fundamental design patterns. We then show you how to build asynchronous control flow patterns with callbacks, promises and async/await. Next, we dive into Node.js streams, unveiling their power and showing you how to use them at their full capacity. Following streams is an analysis of different creational, structural, and behavioral design patterns that take full advantage of JavaScript and Node.js. Lastly, the book dives into more advanced concepts such as Universal JavaScript, scalability and messaging patterns to help you build enterprise-grade distributed applications. Throughout the book, you’ll see Node.js in action with the help of several real-life examples leveraging technologies such as LevelDB, Redis, RabbitMQ, ZeroMQ, and many others. They will be used to demonstrate a pattern or technique, but they will also give you a great introduction to the Node.js ecosystem and its set of solutions.
Table of Contents (16 chapters)
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The Module System

In Chapter 1, The Node.js Platform, we briefly introduced the importance of modules in Node.js. We discussed how modules play a fundamental role in defining some of the pillars of the Node.js philosophy and its programming experience. But what do we actually mean when we talk about modules and why are they so important?

In generic terms, modules are the bricks for structuring non-trivial applications. Modules allow you to divide the codebase into small units that can be developed and tested independently. Modules are also the main mechanism to enforce information hiding by keeping private all the functions and variables that are not explicitly marked to be exported.

If you come from other languages, you have probably seen similar concepts being referred to with different names: package (Java, Go, PHP, Rust, or Dart), assembly (.NET), library (Ruby), or unit (Pascal dialects). The terminology is not perfectly interchangeable because every language or ecosystem comes with its own unique characteristics, but there is a significant overlap between these concepts.

Interestingly enough, Node.js currently comes with two different module systems: CommonJS (CJS) and ECMAScript modules (ESM or ES modules). In this chapter, we will discuss why there are two alternatives, we will learn about their pros and cons, and, finally, we will analyze several common patterns that are relevant when using or writing Node.js modules. By the end of this chapter, you should be able to make pragmatic choices about how to use modules effectively and how to write your own custom modules.

Getting a good grasp of Node.js' module systems and module patterns is very important as we will rely on this knowledge in all the other chapters of this book.

In short, these are the main topics we will be discussing throughout this chapter:

  • Why modules are necessary and the different module systems available in Node.js
  • CommonJS internals and module patterns
  • ES modules (ESM) in Node.js
  • Differences and interoperability between CommonJS and ESM

Let's begin with why we need modules.