Book Image

Mastering JavaScript Object-Oriented Programming

Book Image

Mastering JavaScript Object-Oriented Programming

Overview of this book

ECMAScript 6 introduces several new Object-Oriented features that drastically change the way developers structure their projects. Web developers now have some advanced OOP functionality at their disposal to build large-scale applications in JavaScript. With this book, we'll provide you with a comprehensive overview of OOP principles in JavaScript and how they can be implemented to build sophisticated web applications. Kicking off with a subtle refresher on objects, we'll show you how easy it is to define objects with the new ES6 classes. From there, we'll fly you through some essential OOP principles, forming a base for you to get hands-on with encapsulation. You'll get to work with the different methods of inheritance and we'll show you how to avoid using inheritance with Duck Typing. From there, we'll move on to some advanced patterns for object creation and you'll get a strong idea of how to use interesting patterns to present data to users and to bind data. We'll use the famous promises to work with asynchronous processes and will give you some tips on how to organize your code effectively. You'll find out how to create robust code using SOLID principles and finally, we'll show you how to clearly define the goals of your application architecture to get better, smarter, and more effective coding. This book is your one-way ticket to becoming a JavaScript Jedi who can be counted on to deliver flexible and maintainable code.
Table of Contents (18 chapters)
Mastering JavaScript Object-Oriented Programming
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface

The Interface Segregation Principle


When designing the interface of an object, we should limit to define what is strictly necessary, avoiding carrying around stuff that is not used. This is, in a nutshell, the Interface Segregation Principle, whose official version says:

Clients should not be forced to depend on methods they do not use.

Although JavaScript does not support interfaces as abstract types to define contracts through a typing system, as we saw in Chapter 5, Defining Contracts with Duck Typing, it may somehow be emulated through Duck Typing. In any case, this principle does not refer to the interfaces as a pure syntactic element, but to the whole set of public properties and methods of an object.

In the definition of our object interfaces, therefore, we should be careful to only define what actually is necessary. This avoids the exposure of members that could create ambiguity and confusion.

Let's consider the following code:

function Discounter(min, max, discountPercentage, gadget...