Book Image

Mastering JavaScript Functional Programming - Second Edition

By : Federico Kereki
Book Image

Mastering JavaScript Functional Programming - Second Edition

By: Federico Kereki

Overview of this book

Functional programming is a paradigm for developing software with better performance. It helps you write concise and testable code. To help you take your programming skills to the next level, this comprehensive book will assist you in harnessing the capabilities of functional programming with JavaScript and writing highly maintainable and testable web and server apps using functional JavaScript. This second edition is updated and improved to cover features such as transducers, lenses, prisms and various other concepts to help you write efficient programs. By focusing on functional programming, you’ll not only start to write but also to test pure functions, and reduce side effects. The book also specifically allows you to discover techniques for simplifying code and applying recursion for loopless coding. Gradually, you’ll understand how to achieve immutability, implement design patterns, and work with data types for your application, before going on to learn functional reactive programming to handle complex events in your app. Finally, the book will take you through the design patterns that are relevant to functional programming. By the end of this book, you’ll have developed your JavaScript skills and have gained knowledge of the essential functional programming techniques to program effectively.
Table of Contents (17 chapters)
Technical Requirements

Ensuring Purity - Immutability

In Chapter 4, Behaving Properly – Pure Functions, when we considered pure functions and their advantages, we saw that side effects such as modifying a received argument or a global variable were frequent causes of impurity. Now, after several chapters dealing with many aspects and tools of FP, let's talk about the concept of immutability: how to work with objects in such a way that accidentally modifying them will become harder or, even better, impossible.

We cannot force developers to work in a safe, guarded way, but if we find some way to make data structures immutable (meaning that they cannot be directly changed, except through some interface that never allows us to modify the original data and produces new objects instead), then we'll have an enforceable solution. In this chapter, we will look at two distinct approaches...