JavaScript-mancy: Object-Oriented Programming
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JavaScript-mancy: Object-Oriented Programming

Mastering the Arcane Art of Summoning Objects in JavaScript for C# Developers

About the Book

This is the second book of the JavaScript-mancy series. Within its mysterious pages you'll find:

  • A great introduction to OOP in JavaScript full of fantasy inspired examples and exercises
  • A detailed look at the pillars of OOP in JavaScript adapted for developers with a C# background
  • An awesome walkthrough of how to achieve classical inheritance in JavaScript with and without ES6 classes
  • A step beyond classical inheritance into new OOP paradigms that take advantage of the dynamic nature of JavaScript to bring super flexibility and composability into your apps
  • A look into the obscure object internals and meta-programming with the new Reflect API, Proxies and Symbols
  • A thorough introduction to TypeScript and how it can boost your developer productivity
  • A lot of references to C# that will make it super easy for C# and Java developers to wrap their heads around JavaScript and its quirks. (This also extends to developers familiar with strongly typed languages)
  • A breathtaking story of EPIC proportions and awkward sense of humor...

Imagine... imagine you lived in a world were you could use JavaScript to change the universe around you, to tamper with the threads that compose reality as you know it and do anything that you can imagine. Well, welcome to the world of JavaScript-mancy, where wizards, also known as JavaScriptmancers, control the arcane winds of magic wielding JavaScript to and fro and command the very fabric of reality.

We, programmers, sadly do not live in such a world. But we do have a measure of magic in ourselves, we have the skills and power to create things out of nothingness. And even if we cannot throw fireballs or levitate (yet), we can definitely change/improve/enhance reality and the universe around us with our little creations. Ain't that freaking awesome? 

Well, I hope this book inspires you to continue creating, and using this beautiful skill we share, this time, with JavaScript ;).

For many years JavaScript has been frowned upon and looked down on by many developers due to its quirky nature, obscure behaviors and many WTFs that populate its hairy APIs and operations.

Frown upon no more! For with modern design patterns, libraries, tools and the long awaited ECMAScript 6 (ES6, ES2015) writing JavaScript is now a pleasure.

Join me at the school of JavaScript-mancy as we travel along the modern landscape of writing JavaScript in 2015 and beyond, as we discover the organic evolution of this beautiful language and its thriving ecosystem, and delve in the latest features/spells/incantations of the JavaScript Arcana.

You my friend, can no longer ignore JavaScript. JavaScript is the most deployed language on earth, a beautiful and expressive language that supports many paradigms and which has a thriving community that continuously expands and improves its ecosystem with patterns, libraries, frameworks and tools. You don't want to miss this train.

But JavaScript, though forgiving and specially conceived to be easy to learn, can be either daunting for us that have a strongly-typed mindset and come from languages such as C# or Java or, more often, laughed at as a toy.

For you who consider it daunting and hate working with it worry not! I will show you the most common misconceptions and all the patterns you need to know to become as fluent in JavaScript as you are in C#.

For you who consider it a toy language, something associated not with real programming but with copy-paste coding or scripting to add flare to websites, I will show you all the different patterns and programming paradigms that JavaScript supports and which make it just as good and powerful as C#.

Let's get our JavaScript adventure started!

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  • Categories

    • JavaScript
    • .NET
    • Computers and Programming
    • Web Development
    • Software Engineering
    • Software Architecture
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About the Author

Jaime González García
Jaime González García

Software Developer and UX guy, speaker, author & defender of all things nerd

Jaime is a software developer and UX designer who loves building stuff. Sometimes to solve a problem, sometimes for the challenge, but more often because he just loves creating things for the sake of it. And the quirkier and weirder, the better. He specially enjoys mixing carefully crafted software with visually appealing aesthetics.

Obnoxiously joyful dude, fake extrovert, undercover nerd, Jaime works as a Front-end Software Engineer at Google. He spends part of his time as a Developer Relations in the Nordics developer community. He speaks at conferences, writes articles, runs workshops and talks to developers and companies about how they can do cool things with JavaScript. He also arranges developer community events in Stockholm as a way to support and encourage the thriving local dev ecosystem.

In his spare time, he builds his own products, writes the JavaScript-mancy series of books and blogs at He loves spending time with his beloved wife Malin and son Teo, drawing, writing, reading fantasy and sci-fi, and lifting heavy weights.

Jaime González García

Episode 127

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About the Contributors

Artur Mizera
Artur Mizera

Technical Reviewer

Artur is a passionate software developer who has built various web applications for small as well as enterprise companies.

Sometimes he recollects the good, old times when jQuery was in beta, just about to be released as 1.0 and nobody even knew what SPA stood for... Everyday he tries to get better with modern front- end development and software craftsmanship.

Currently he works as Senior Applications Developer at Oracle. When he gets home he plays around with side projects, open source or gets outside and does some running. 

Reader Testimonials

Matt Ruby
Matt Ruby

Principal Software Engineer at Bluestem Brands, Inc.

This has been the best book I've read on OOP in JS. Most books that cover this subject use obtuse examples. Jaime's examples cover common cases and how to solve them while embracing javascript instead of fighting it. I've been using js for years and I've learned many new techniques from this book. I highly recommend it!

Kári Tristan Helgason
Kári Tristan Helgason

Software Engineer at Google and Technical Reviewer for this book

This book will not only teach you things you didn't know about object-oriented programming in JavaScript, it will also keep you entertained while doing so! Even if you have no interest in object-oriented programming, and have years of experience with JavaScript, I can guarantee that you will learn new patterns and ways of thinking about a problem from this book. Jaime is fantastic at breaking down concepts and exploring them from different angles until they fall into place. I really enjoyed it.

Table of Contents

    • About The Author
    • About the Technical Reviewers
    • Prelude
      • A Note to the Illustrious Readers of JavaScript-mancy: Getting Started
      • A Story About Why I Wrote This Book
      • Why Should You Care About JavaScript?
      • What is the Goal of This Book?
      • What is the Goal of The JavaScript-mancy Series?
      • Why JavaScript-mancy?
      • Is This Book For You?
      • How is The Book Organized?
      • How Are The JavaScript-mancy Series Organized? What is There in the Rest of the Books?
      • Understanding the Code Samples in This Book
      • A Note About ECMAScript 5 (ES5) and ES6, ES7, ES8 and ESnext within The Book
      • A Note Regarding the Use of var, let and const
      • A Note About the Use of Generalizations in This Book
      • Do You Have Any Feedback? Found Any Error?
      • A Final Word From the Author
    • Once Upon a Time…
  • Tome II. JavaScriptmancy and OOP: The Path of The Summoner
    • Introduction to the Path of Summoning and Commanding Objects (aka OOP)
      • Let me Tell You About OOP in JavaScript
      • C# Classes in JavaScript
      • OOP Beyond Classes
      • Combining Classes with Object Composition
      • The Path of the Object Summoner Step by Step
      • Concluding
    • Summoning Fundamentals: Encapsulation and Information Hiding
      • Let’s get Started With The Basics of OOP!
      • Encapsulation: Creating Objects in JavaScript
      • Object Initializers
      • Constructor Functions and the New Operator
      • Data Hiding in JavaScript
      • Object Initializers vs Constructor Functions
      • Object Factories vs Constructor Functions
      • Concluding
      • Exercises
    • Summoning Fundamentals: Prototypical Inheritance
      • You Don’t Repeat Yourself. Inheritance!
      • Classical Inheritance vs Prototypical Inheritance
      • JavaScript Prototypical Inheritance
      • Object Prototypes
      • Object Prototypes with Object.Create or OLOO
      • Defining Prototypes with Constructor Functions
      • Creating Longer Prototype Chains
      • What About Concatenative Protypical Inheritance?
      • Object Initializers vs Object.create vs Constructor Functions
      • Concluding
      • Exercises
    • Summoning Fundamentals: Polymorphism
      • Polymorphism Means Many Forms
      • Polymorphism in C#
      • Polymorphism in JavaScript
      • Concluding
      • Exercises
    • White Tower Summoning: Mimicking C# Classical Inheritance in JavaScript
      • Ever Heard of Classical Inheritance?
      • Emulating a C# Class in JavaScript
      • Constructor Function + Prototype = Class
      • Mimicking Classical Inheritance in JavaScript
      • Simplifying Classical Inheritance in ES5
      • Concluding
      • Exercises
    • White Tower Summoning Enhanced: The Marvels of ES6 Classes
      • Create These Units Faster with ES6 Classes!
      • From ES5 “Classes” to ES6 Classes
      • Prototypical Inheritance via Extends
      • Overriding Methods in ES6 Classes
      • Static Members and Methods
      • ES6 Classes and Information Hiding
      • ES6 Classes Behind the Curtain
      • Concluding
      • Exercises
    • Black Tower Summoning: Objects Interweaving Objects with Mixins
      • The Problem With Classes and Classical Inheritance…
      • Free Yourself From Classes With Object Composition and Mixins
      • Limitations of Mixins as Objects
      • Functional Mixins
      • Combining Mixins with ES6 Classes
      • Object.assign in Depth
      • Object.assign Alternatives for ES5 JavaScript-mancers
      • Concluding
      • Exercises
    • Black Tower Summoning: Safer Object Composition with Traits
      • An Improvement Over Mixins
      • Traits
      • Traits with traits.js
      • Composing Traits
      • What Happens When You Miss Required Properties?
      • Resolving Name Conflicts
      • Traits and Data Privacy
      • High Integrity Objects With Immutable Traits
      • Traits vs Mixins
      • Concluding
      • Exercises
    • Black Tower Summoning: Next Level Object Composition With Stamps
      • I Call Them Stamps
      • What are Stamps?
      • Stamps OOP Embraces JavaScript
      • Stamps By Example
      • Stamp Composition
      • Stamp Fluent API
      • Concluding: Stamps vs Mixins vs Traits
      • Exercises
    • Object Internals: The Secrets of Objects
      • A Nifty Trick… Object Internals
      • All your Objects Are Belong to Object
      • Defining Properties with Object.defineProperty
      • Defining Multiple Properties with Object.defineProperties
      • Beautiful Property Manipulation with ESnext Decorators
      • Class And Method Decorators
      • Create Objects With Object.create And Property Descriptors
      • Metaprogramming
      • Other Useful Object Methods
      • Concluding
      • Exercises
    • More Metaprogramming with Reflect, Proxies and Symbols
      • How Good Are You at Reflection?
      • ES6 Reflect
      • Reflection? What is reflection?
      • ES6 Proxies
      • ES6 Symbols and Meta-programming
      • Concluding
      • Exercises
    • TypeScript
      • You Shall Only Use Types!
      • JavaScript + Types = Awesome Dev Productivity
      • Any JavaScript is Valid TypeScript
      • So, What Are The Advantages and Disadvantages of TypeScript?
      • Setting up a Simple TypeScript project
      • Cool TypeScript Features
      • Type Annotations In TypeScript
      • Working with TypeScript in Real World Applications
      • Concluding
      • Exercises
  • Tome II. Epilogue
    • Thank you!
  • References and Appendix
    • Appendix A. On the Art of Summoning Servants and Critters, Or Understanding The Basics of JavaScript Objects
      • An Army of Objects
      • Object Initializers (a.k.a. Object Literals)
      • Creating Objects With Factories
      • Data Privacy in JavaScript
      • ES6 Improves Object Initializers
      • ES6 Symbols and Data Privacy
      • Concluding
      • Exercises
    • Appendix B. Mysteries of the JavaScript Arcana
      • A Couple of Tips About JavaScript Quirks and Gotchas
      • A Quick Refresher of the JavaScript Arcana 101
      • This, Your Most Dangerous Foe
      • Global Scope by Default and Namespacing in JavaScript
      • Type Coercion Madness
      • Using JavaScript in Strict Mode
      • Concluding
      • Exercises
    • Appendix C. More Useful Function Patterns: Function Overloading
      • Have you Heard About The Marvels Of Overloading?
      • The Problem with Function Overloading in JavaScript
      • How Do We Do Function Overloading Then?
      • Function Overloading by Inspecting Arguments
      • Using an Options Object
      • Relying on ES6 Defaults
      • Taking Advantage of Polymorphic Functions
      • Concluding
      • Exercises
    • Appendix D. Setting Up Your Developing Environment For ES6
      • Using ES6 with Node.js
      • ES6 and Modern Browsers
      • Real-World ES6 Development Environments
    • Appendix E. Fantasy Glossary
    • References
      • Specifications
      • Books
      • White papers
      • Articles
  • Notes

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