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

Persistent data structures

If every time you want to change something in a data structure, you just go and change it, your code will be full of side-effects. On the other hand, copying complete structures every time is a waste of time and space. There's a middle way, with persistent data structures, which, if handled correctly, let you apply changes while creating new structures, in an efficient way.

Working with lists

Let's consider a simple procedure: suppose you have a list, and you want to add a new element to it. How would you do it? We can assume each node is a NodeList object.

class ListNode {
   constructor(value, next = null) {
       this.value = value; = next;

A possible list would be as follows, where a list variable would point to the first element. See figure 10.1:

Figure 10.1. The initial list. (Can you tell what is missing in this list, and where?)

If you wanted to add D between B and F (this is something musicians will understand: we have here the Circle...