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

Pure functions

Pure functions behave in the same way as mathematical functions and provide diverse benefits. A function is pure if it satisfies two conditions:

  • Given the same arguments, the function always calculates and returns the same result: This should be true no matter how many times it's invoked or under which conditions you call it. This result cannot depend on any outside information or state, which could change during the program execution and cause it to return a different value. Nor can the function result depend on I/O results, random numbers, some other external variable, or a value that is not directly controllable.
  • When calculating its result, the function doesn't cause any observable side effects: This includes output to I/O devices, the mutation of objects, changes to a program's state outside of the function, and so on.

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