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

Going the straightforward JavaScript way

One of the biggest causes of side effects was the possibility of a function modifying global objects or its arguments. All non-primitive objects are passed as references, so if/when you modify them, the original objects will be changed. If we want to stop this (without just depending on the goodwill and clean coding of our developers), we may want to consider some straightforward JavaScript techniques to disallow those side effects:

  • Avoiding mutator functions that directly modify the object that they are applied to
  • Using const declarations to prevent variables from being changed
  • Freezing objects so that they can't be modified in any way
  • Creating (changed) clones of objects to avoid modifying the original
  • Using getters and setters to control what is changed and how
  • Using a functional concept—lenses—to access and set attributes...