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Mastering JavaScript Functional Programming

You're reading from   Mastering JavaScript Functional Programming In-depth guide for writing robust and maintainable JavaScript code in ES8 and beyond

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Product type Paperback
Published in Nov 2017
Publisher Packt
ISBN-13 9781787287440
Length 386 pages
Edition 1st Edition
Languages
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Author (1):
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Federico Kereki Federico Kereki
Author Profile Icon Federico Kereki
Federico Kereki
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Table of Contents (22) Chapters Close

Dedication
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
1. Becoming Functional – Several Questions FREE CHAPTER 2. Thinking Functionally - A First Example 3. Starting Out with Functions - A Core Concept 4. Behaving Properly - Pure Functions 5. Programming Declaratively - A Better Style 6. Producing Functions - Higher-Order Functions 7. Transforming Functions - Currying and Partial Application 8. Connecting Functions - Pipelining and Composition 9. Designing Functions - Recursion 10. Ensuring Purity - Immutability 11. Implementing Design Patterns - The Functional Way 12. Building Better Containers - Functional Data Types 1. Bibliography
2. Answers to Questions

Chapter 10. Ensuring Purity - Immutability

In Chapter 4, Behaving Properly - Pure Functions, when we considered pure functions and their advantages, we saw that side-effects such as modifying a received argument or a global variable were frequent causes for impurity. Now, after several chapters dealing with many aspects and tools of FP, let's get to the concept of immutability: how to work with objects in such a way that accidentally modifying them will become harder or, even better, impossible.

We cannot force developers to work in a safe, guarded way, but if we find some way to make data structures immutable (meaning that they cannot be directly changed, except through some interface that never allows modifying the original data, but produces new objects instead) then we'll have an enforceable solution. In this chapter, we will see two distinct approaches to working with such immutable objects and data structures:

  • Basic JS ways, such as freezing objects, plus cloning to create new ones instead...
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