Book Image

Learning TypeScript 2.x - Second Edition

By : Remo H. Jansen
Book Image

Learning TypeScript 2.x - Second Edition

By: Remo H. Jansen

Overview of this book

TypeScript is an open source and cross-platform statically typed superset of JavaScript that compiles to plain JavaScript and runs in any browser or host. This book is a step-by-step guide that will take you through the use and benefits of TypeScript with the help of practical examples. You will start off by understanding the basics as well as the new features of TypeScript 2.x. Then, you will learn how to work with functions and asynchronous programming APIs. You will continue by learning how to resolve runtime issues and how to implement TypeScript applications using the Object-oriented programming (OOP) and functional programming (FP) paradigms. Later, you will automate your development workflow with the help of tools such as Webpack. Towards the end of this book, you will delve into some real-world scenarios by implementing some full-stack TypeScript applications with Node.js, React and Angular as well as how to optimize and test them. Finally, you will be introduced to the internal APIs of the TypeScript compiler, and you will learn how to create custom code analysis tools.
Table of Contents (17 chapters)

Real-world FP

In this section, we are going to explore some open source libraries that can be useful while working in a real-world FP application.


As we have learned in this chapter, one of the main ideas in FP is minimizing the number of places in which state is mutated in our application. However, in JavaScript, objects are not immutable, which we can lead us to mutate the application's state by mistake. For example, we could try to sort an array using the following function:

function sort(arr: number[]) { 
    return arr.sort((a, b) => b - a); 

The preceding function could lead to issues because the sort method mutates the original array. This example is a demonstration of what is known as an implicit...