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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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Toc

Table of Contents (15) Chapters Close

Preface 1. Becoming Functional - Several Questions 2. Thinking Functionally - A First Example FREE CHAPTER 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 13. Bibliography
14. Answers to Questions

Other higher-order functions


Let's end this chapter by considering other sundry functions that provide results such as new finders, decoupling method from objects, and more.

Turning operations into functions

We have already seen several cases in which we needed to write a function just to add or multiply a pair of numbers. For example, in the Summing an array section of Chapter 5, Programming Declaratively - A Better Style, we had to write code equivalent to the following:

const mySum = myArray.reduce((x, y) => x + y, 0);

In the same chapter, in the section Working with ranges, to calculate a factorial, we then needed this:

const factorialByRange = n => range(1, n + 1).reduce((x, y) => x * y, 1);

It would have been easier if we could just turn a binary operator into a function that calculates the same result. The preceding two examples could have been written more succinctly, shown as follows:

const mySum = myArray.reduce(binaryOp("+"), 0);
const factorialByRange = n => range(1, n...
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