Book Image

Mastering JavaScript Functional Programming

By : Federico Kereki
Book Image

Mastering JavaScript Functional Programming

By: Federico Kereki

Overview of this book

Functional programming is a programming paradigm for developing software using functions. Learning to use functional programming is a good way to write more concise code, with greater concurrency and performance. The JavaScript language is particularly suited to functional programming. This book provides comprehensive coverage of the major topics in functional programming with JavaScript to produce shorter, clearer, and testable programs. You’ll delve into functional programming; including writing and testing pure functions, reducing side-effects, and other features to make your applications functional in nature. Specifically, we’ll explore techniques to simplify coding, apply recursion for loopless coding, learn ways to achieve immutability, implement design patterns, and work with data types. By the end of this book, you’ll have developed the JavaScript skills you need to program functional applications with confidence.
Table of Contents (22 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback
Connecting Functions - Pipelining and Composition
Answers to Questions


The first set of operations 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() operations; 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 usage of these higher-order functions, trying to avoid them, with longer code, and more probability of bugs simply doesn't make much sense.

Let's start by considering the preceding list of functions in order, starting by the most general of all--which, as we'll see, can even be used to emulate the rest of the transformations in this chapter!

Reducing an array to a value...