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


The first set of operations that we are going to consider work on an array and process it in the base of a function to produce some results. There are several possible results: a single value with the reduce() operation; a new array with map(); or just about any kind of result with forEach().

If you Google around, you will find some articles that declare that these functions are not efficient because a loop done by hand can be faster. This, while possibly true, is practically irrelevant. Unless your code really suffers from speed problems and you are able to measure that the slowness derives from the use of these higher-order functions, trying to avoid them using longer code, with a higher probability of bugs, simply doesn't make much sense.

Let's start by considering the preceding list of functions in order, starting with the most general of all, which...