Book Image

Mastering TypeScript - Fourth Edition

By : Nathan Rozentals
4.7 (3)
Book Image

Mastering TypeScript - Fourth Edition

4.7 (3)
By: Nathan Rozentals

Overview of this book

TypeScript is both a language and a set of tools to generate JavaScript, designed by Anders Hejlsberg at Microsoft to help developers write enterprise-scale JavaScript. Mastering Typescript is a golden standard for budding and experienced developers. With a structured approach that will get you up and running with Typescript quickly, this book will introduce core concepts, then build on them to help you understand (and apply) the more advanced language features. You’ll learn by doing while acquiring the best programming practices along the way. This fourth edition also covers a variety of modern JavaScript and TypeScript frameworks, comparing their strengths and weaknesses. You'll explore Angular, React, Vue, RxJs, Express, NodeJS, and others. You'll get up to speed with unit and integration testing, data transformation, serverless technologies, and asynchronous programming. Next, you’ll learn how to integrate with existing JavaScript libraries, control your compiler options, and use decorators and generics. By the end of the book, you will have built a comprehensive set of web applications, having integrated them into a single cohesive website using micro front-end techniques. This book is about learning the language, understanding when to apply its features, and selecting the framework that fits your real-world project perfectly.
Table of Contents (19 chapters)
17
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18
Index

Interfaces

In Chapter 1, Up and Running Quickly, we discussed how TypeScript uses duck typing to assess if two objects are compatible. These typing rules govern whether an object can be assigned to another and compares the properties of one object to the other.

Interfaces provide us with a mechanism to define what properties an object must implement and is, therefore, a way for us to define a custom type. By defining an interface, we are describing the properties and functions that an object is expected to have in order to be used by our code.

To illustrate these concepts, consider the following code:

interface IIdName {
    id: number;
    name: string;
}

Here, we have used the interface keyword to define a TypeScript interface named IIdName. This interface describes an object that has an id property of type number, and a name property of type string. Once we have defined an interface, we can use it in the same way as a primitive type, as follows:

let idObject...