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Node.js  Design Patterns
Node.js  Design Patterns

Node.js Design Patterns: Master best practices to build modular and scalable server-side web applications , Second Edition

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Profile Icon Purra Profile Icon Luciano Mammino Profile Icon Mario Casciaro
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Full star icon Full star icon Full star icon Full star icon Half star icon 4.6 (32 Ratings)
Paperback Jul 2016 526 pages 2nd Edition
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Arrow left icon
Profile Icon Purra Profile Icon Luciano Mammino Profile Icon Mario Casciaro
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S$74.99
Full star icon Full star icon Full star icon Full star icon Half star icon 4.6 (32 Ratings)
Paperback Jul 2016 526 pages 2nd Edition
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S$41.98 S$59.99
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Node.js Design Patterns

Chapter 2. Node.js Essential Patterns

Embracing the asynchronous nature of Node.js is not trivial at all, especially if coming from a language such as PHP where it is not usual to deal with asynchronous code.

In synchronous programming, we are used to the concept of imagining code as a series of consecutive computing steps defined to solve a specific problem. Every operation is blocking, which means that only when an operation is completed is it possible to execute the next one. This approach makes the code easy to understand and debug.

Instead, in asynchronous programming, some operations, such as reading a file or performing a network request, can be executed as an operation in the background. When an asynchronous operation is invoked, the next one is executed immediately, even if the previous operation has not finished yet. The operations pending in the background can complete at any time, and the whole application should be programmed to react in the proper way when an asynchronous...

The callback pattern

Callbacks are the materialization of the handlers of the reactor pattern, which we introduced in the previous chapter. They are one of those imprints that give Node.js its distinctive programming style. Callbacks are functions that are invoked to propagate the result of an operation and this is exactly what we need when dealing with asynchronous operations. They do replace the use of the return instruction that always executes synchronously. JavaScript is a great language to represent callbacks, because as we have seen, functions are first class objects and can be easily assigned to variables, passed as arguments, returned from another function invocation or stored into data structures. Another ideal construct for implementing callbacks is closures. With closures, we can in fact reference the environment in which a function was created; we can always maintain the context in which the asynchronous operation was requested, no matter when or where its callback is invoked...

The module system and its patterns

Modules are the bricks for structuring non-trivial applications, but also the main mechanism to enforce information hiding by keeping private all the functions and variables that are not explicitly marked to be exported. In this section, we will introduce the Node.js module system and its most common usage patterns.

The revealing module pattern

One of the major problems with JavaScript is the absence of namespacing. Programs that run in the global scope polluting it with data that comes from both internal application code and dependencies. A popular technique to solve this problem is called the revealing module pattern, and it looks like the following:

const module = (() => { 
  const privateFoo = () => {...}; 
  const privateBar = []; 
 
  const exported = { 
    publicFoo: () => {...}, 
    publicBar: () => {...} 
  }; 
 
  return exported; 
})(); 
console.log(module);

This pattern leverages a self-invoking function to create a private scope...

The observer pattern

Another important and fundamental pattern used in Node.js is the observer pattern. Together with the reactor, callbacks, and modules, the observer pattern is one of the pillars of the platform and an absolute prerequisite for using many node-core and userland modules.

Observer is an ideal solution for modeling the reactive nature of Node.js and a perfect complement for callbacks. Let's give a formal definition as follows:

Pattern (observer) defines an object (called subject), which can notify a set of observers (or listeners), when a change in its state happens.

The main difference from the callback pattern is that the subject can actually notify multiple observers, while a traditional continuation-passing style callback will usually propagate its result to only one listener, the callback.

The EventEmitter class

In traditional object-oriented programming, the observer pattern requires interfaces, concrete classes, and a hierarchy; in Node.js, all becomes much simpler...

Summary

In this chapter, we first learnt the difference between synchronous and asynchronous code. Then we explored how to use the callback and the event emitter patterns to deal with some basic asynchronous scenarios. We also learned the main differences between the two patterns and when one is more suitable than the other to address a specific problem. We just made the first steps toward more advanced asynchronous patterns.

In the next chapter we will have a look at more complex scenarios, learning how to leverage the callback and the event emitter patterns to deal with advanced asynchronous control flows.

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Key benefits

  • Create reusable patterns and modules by leveraging the new features of Node.js .
  • Understand the asynchronous single thread design of node and grasp all its features and patterns to take advantage of various functions.
  • This unique guide will help you get the most out of Node.js and its ecosystem.

Description

Node.js is a massively popular software platform that lets you use JavaScript to easily create scalable server-side applications. It allows you to create efficient code, enabling a more sustainable way of writing software made of only one language across the full stack, along with extreme levels of reusability, pragmatism, simplicity, and collaboration. Node.js is revolutionizing the web and the way people and companies create their software. In this book, we will take you on a journey across various ideas and components, and the challenges you would commonly encounter while designing and developing software using the Node.js platform. You will also discover the "Node.js way" of dealing with design and coding decisions. The book kicks off by exploring the basics of Node.js describing it's asynchronous single-threaded architecture and the main design patterns. It then shows you how to master the asynchronous control flow patterns,and the stream component and it culminates into a detailed list of Node.js implementations of the most common design patterns as well as some specific design patterns that are exclusive to the Node.js world.Lastly, it dives into more advanced concepts such as Universal Javascript, and scalability' and it's meant to conclude the journey by giving the reader all the necessary concepts to be able to build an enterprise grade application using Node.js.

Who is this book for?

The book is meant for developers and software architects with a basic working knowledge of JavaScript who are interested in acquiring a deeper understanding of how to design and develop enterprise-level Node.js applications. Basic knowledge of Node.js is also helpful to get the most out of this book.

What you will learn

  • Design and implement a series of server-side JavaScript patterns so you understand why and when to apply them in different use case scenarios
  • Become comfortable with writing asynchronous code by leveraging constructs such as callbacks, promises, generators and the async-await syntax
  • Identify the most important concerns and apply unique tricks to achieve higher scalability and modularity in your Node.js application
  • Untangle your modules by organizing and connecting them coherently
  • Reuse well-known techniques to solve common design and coding issues
  • Explore the latest trends in Universal JavaScript, learn how to write code that runs on both Node.js and the browser and leverage React and its ecosystem to implement universal applications
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Publication date : Jul 18, 2016
Length: 526 pages
Edition : 2nd
Language : English
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Table of Contents

11 Chapters
1. Welcome to the Node.js Platform Chevron down icon Chevron up icon
2. Node.js Essential Patterns Chevron down icon Chevron up icon
3. Asynchronous Control Flow Patterns with Callbacks Chevron down icon Chevron up icon
4. Asynchronous Control Flow Patterns with ES2015 and Beyond Chevron down icon Chevron up icon
5. Coding with Streams Chevron down icon Chevron up icon
6. Design Patterns Chevron down icon Chevron up icon
7. Wiring Modules Chevron down icon Chevron up icon
8. Universal JavaScript for Web Applications Chevron down icon Chevron up icon
9. Advanced Asynchronous Recipes Chevron down icon Chevron up icon
10. Scalability and Architectural Patterns Chevron down icon Chevron up icon
11. Messaging and Integration Patterns Chevron down icon Chevron up icon

Customer reviews

Top Reviews
Rating distribution
Full star icon Full star icon Full star icon Full star icon Half star icon 4.6
(32 Ratings)
5 star 75%
4 star 15.6%
3 star 3.1%
2 star 6.3%
1 star 0%
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Amazon Customer Dec 11, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
skills to the next level. I was at an intermediate level not sure where to go next and this was the answer! I think (no offense) that whoever said that this is not as design pattern specific as the name implies does not actually understand what the term design patterns really means or must have a different definition for it that I don't know of. I completely disagree with you. In almost every chapter there is a design pattern being discussed. I can't get tired of reading this book! I would highly recommend it.
Amazon Verified review Amazon
Ajay Kumar Mar 21, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
I purchased the book after seeing its rating and numbers of reviews in amazon.com.I have a good level development experience in node.js server application, even then found this extremely helpful in reading only first 2 chapters. It is very well structured and written. It cleared many of my old confusions and provided more understanding of node.js along with ES6 till I read.I thanks its writer to provide such a good information about the subject without any confusion.I will strongly recommend to read the book who wants deeper information and build a strong node.js application.
Amazon Verified review Amazon
Shark Sep 03, 2016
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Very useful ideas, practices and techniques. The book is easy to follow and the examples are progressive leading you to the final solution.I really appreciate this book and I recommend it to all developers that want to learn how to be proficient with node.js.
Amazon Verified review Amazon
K Smith Sep 26, 2016
Full star icon Full star icon Full star icon Full star icon Full star icon 5
I was looking for exactly a book like this. This book helped me become a better Node.js developer. The design patterns and ideas will really speed up your code.
Amazon Verified review Amazon
Steven Myers Aug 22, 2017
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This is a very good book that introduces the reader to common javascript patterns. Good for all skill levels and well written. Has an interesting section on Dependency Injection.
Amazon Verified review Amazon
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