Book Image

Hands-On Functional Programming with TypeScript

By : Remo H. Jansen
Book Image

Hands-On Functional Programming with TypeScript

By: Remo H. Jansen

Overview of this book

Functional programming is a powerful programming paradigm that can help you to write better code. However, learning functional programming can be complicated, and the existing literature is often too complex for beginners. This book is an approachable introduction to functional programming and reactive programming with TypeScript for readers without previous experience in functional programming with JavaScript, TypeScript , or any other programming language. The book will help you understand the pros, cons, and core principles of functional programming in TypeScript. It will explain higher order functions, referential transparency, functional composition, and monads with the help of effective code examples. Using TypeScript as a functional programming language, you’ll also be able to brush up on your knowledge of applying functional programming techniques, including currying, laziness, and immutability, to real-world scenarios. By the end of this book, you will be confident when it comes to using core functional and reactive programming techniques to help you build effective applications with TypeScript.
Table of Contents (14 chapters)
5
The Runtime – Closures and Prototypes

Asynchronous functions – async and await

Asynchronous functions are a TypeScript feature that arrived with the TypeScript 1.6 release. Developers can use the await keyword to wait for an asynchronous operation to be completed without blocking the normal execution of the program.

Using asynchronous functions helps to increase the readability of a piece of code when compared with the use of promises or callbacks but, technically, we can achieve the same features using both promises and asynchronous functions.

Let's take a look at a basic async/await example:

let p = Promise.resolve(3);

async function fn(): Promise<number> {
var i = await p; // 3
return 1 + i; // 4
}

fn().then((r) => console.log(r)); // 4

The preceding code snippet declares a promise named p. This promise represents a future result. As we can see, the fn function is preceded by the async keyword...