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)

Prototypes

When we compile a TypeScript program, all classes and objects become JavaScript objects. However, sometimes we may encounter an unexpected behavior at runtime, even if the compilation was completed without errors. To be able to identify and understand the cause of this behavior, we need a good understanding of the JavaScript runtime. One of the main concepts that we need to understand is how inheritance works at runtime.

The runtime inheritance system uses a prototypal inheritance model. In a prototypal inheritance model, objects inherit from objects, and there are no classes available. However, we can use prototypes to simulate classes. Let's see how it works.

At runtime, every JavaScript object has an internal property called prototype. The value of the prototype attribute is an object, which contains some attributes (data) and methods (behavior).

In TypeScript...