#### 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.
Dedication
Title Page
Credits
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Preface
Free Chapter
Becoming Functional – Several Questions
Thinking Functionally - A First Example
Starting Out with Functions - A Core Concept
Behaving Properly - Pure Functions
Programming Declaratively - A Better Style
Producing Functions - Higher-Order Functions
Transforming Functions - Currying and Partial Application
Connecting Functions - Pipelining and Composition
Designing Functions - Recursion
Ensuring Purity - Immutability
Implementing Design Patterns - The Functional Way
Building Better Containers - Functional Data Types
Bibliography
6.1. A border case. What happens with our `getField()` function if we apply it to a null object? What should its behavior be? If necessary, modify the function.
6.2. How many? How many calls would be needed to calculate `fib(50)` without memoizing? For example, to calculate `fib(0)` or `fib(1)`, one call is enough with no further recursion needed, and for `fib(6)` we saw that 25 calls were required. Can you find a formula to do this calculation?
6.3. A randomizing balancer. Write a higher-order function `randomizer(fn1, fn2, ...)` that will receive a variable number of functions as arguments, and return a new function that will, on each call, randomly call one of `fn1`, `fn2`, and so on. You could possibly use this to balance calls to different services on a server if each function was able to do an Ajax call. For bonus points, ensure that no function will be called twice in a row.
6.4. Just say no! In this chapter, we wrote a `not()` function that worked with boolean functions and a `negate()` function...