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


Pipelining and composition are techniques for setting up functions to work in sequence, so the output from a function becomes the input to the next function. There are two ways of looking at this: from a computer point of view and from a mathematical point of view. Usually, most FP texts start with the latter, but since I assume that most readers are closer to computers than to math, let's start with the former.

Piping in Unix/Linux

In Unix/Linux, the execution of a command and passing its output as an input to a second command, whose output will yet the input of a third command, and so on, is called a pipeline. This is quite common, and an application of the philosophy of Unix, as explained in a Bell Laboratories article, written by the creator of the pipelining concept himself, Doug McIlroy:

  1. Make each program do one thing well. To do a new job, build afresh rather than complicating old programs by adding new features.
  2. Expect the output of every program to become the input to another...