Preface

Node.js is considered by many a game-changer—possibly the biggest innovation of the decade in web development. It is loved not just for its technical capabilities, but also for the paradigm shift that it introduced in web development and, in general, in the software development ecosystem.

First, Node.js applications are written in JavaScript, the most adopted language on the web and the only programming language supported natively by every web browser. This aspect enables scenarios such as single-language application stacks and the sharing of code between the server and the client. A single language also helps to reduce the gap between frontend and backend engineers, making backend programming extremely approachable and intuitive for frontend developers. Once you are acquainted with Node.js and JavaScript, you can easily build software for a wide variety of platforms and contexts.

Node.js itself is contributing to the rise and evolution of the JavaScript language. People realize that using JavaScript on the server brings a lot of value, and they are loving it for its pragmatism, for its flexibility, its event-driven approach, and for its hybrid nature, halfway between object-oriented and functional programming.

The second revolutionizing factor is Node.js' single-threaded programming model and its asynchronous architecture. Besides obvious advantages from a performance and scalability point of view, this characteristic changed the way developers approach concurrency and parallelism. Mutexes are replaced by queues, threads by callbacks, and synchronization by causality. These abstractions are generally simpler to adopt than their traditional counterparts, but they are still extremely powerful, allowing developers to be very productive while solving day-to-day challenges.

The last and most important aspect of Node.js lies in its ecosystem: the npm package manager, its constantly growing database of modules, its enthusiastic and helpful community, and most importantly, its very own culture based on simplicity, pragmatism, and extreme modularity.

However, because of these peculiarities, Node.js development gives you a very different feel compared to other server-side platforms, and any developer new to this paradigm will often feel unsure about how to tackle even the most common design and coding problems effectively. Common questions include: How do I organize my code? What's the best way to design this? How can I make my application more modular? How do I handle a set of asynchronous calls effectively? How can I make sure that my application will not collapse while it grows? Or more simply, what's the right way to implement this? Fortunately, Node.js has become a mature enough platform and most of these questions can now be easily answered with a design pattern, a proven coding technique, or a recommended practice. The aim of this book is to guide you through this emerging world of patterns, techniques, and practices, showing you what the proven solutions to the most common problems are and teaching you how to use them as the starting point to building the solution to your particular problem.

By reading this book, you will learn the following:

• The "Node way":

  How to use the right point of view when approaching Node.js development. You will learn, for example, how different traditional design patterns look in Node.js, or how to design modules that do only one thing.

• A set of patterns to solve common Node.js design and coding problems:

  You will be presented with a "Swiss Army knife" of patterns, ready to use in order to efficiently solve your everyday development and design problems.

• How to write scalable and efficient Node.js applications:

  You will gain an understanding of the basic building blocks and principles of writing large and well-organized Node.js applications that can scale. You will be able to apply these principles to novel problems that don't fall within the scope of existing patterns.

• Code in "modern JavaScript":

  JavaScript has been around since 1995, but a lot has changed since its first inception, especially in these last few years. This book will take advantage of the most modern JavaScript features, like the class syntax, promises, generator functions, and async/await, giving you a properly up-to-date experience.

Throughout the book, you will be presented with real-life libraries and technologies, such as LevelDB, Redis, RabbitMQ, ZeroMQ, Express, and many others. They will be used to demonstrate a pattern or technique, and besides making the example more useful, these will also give you great exposure to the Node.js ecosystem and its set of solutions.

Whether you use or plan to use Node.js for your work, your side project, or for an open source project, recognizing and using well-known patterns and techniques will allow you to use a common language when sharing your code and design, and on top of that, it will help you get a better understanding of the future of Node.js and how to make your own contributions a part of it.