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)

Annotations versus decorators

Annotations are a way to add metadata to class declarations. The metadata can then be used by libraries and other development tools, such as inversion of control containers. The annotations API was originally proposed by the Google AtScript team, but annotations are not a standard. However, decorators are a proposed standard for the ECMAScript specification, to annotate and modify classes and properties at design time. Annotations and decorators are pretty much the same:

"Annotations and decorators are nearly the same thing. From a consumer perspective, we have exactly the same syntax. The only thing that differs is that we don't have control over how annotations are added as metadata to our code. A decorator is rather an interface to build something that ends up as annotation. Over a long term, however, we can just focus on decorators,...