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

Chaining and fluent interfaces

When you work with objects or arrays, there is another way of linking the execution of several calls together: by applying chaining. For example, when you work with arrays, if you apply a map() or filter() method, the result is a new array, which you can then apply a new further map() or filter() to, and so forth. We used such methods when we defined the range() function back in the Working with ranges section of Chapter 5, Programming Declaratively – A Better Style:

const range = (start, stop) =>
new Array(stop - start).fill(0).map((v, i) => start + i);

First, we created a new array; then, we applied the fill() method to it, which updated the array in place (side effect) and returned the updated array, to which we finally applied a map() method. The latter method generated a new array, to which we could have applied further mappings...