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
Other Books You May Enjoy
18
Index

Classes

A class is the definition of an object, what data it holds, and what operations it can perform. Classes and interfaces form the cornerstone of object-oriented programming. Let's take a look at a simple class definition, as follows:

class SimpleClass {
    id: number;
    print(): void {
        console.log(`SimpleClass.print() called.`);
    }
}

Here, we have defined a class, using the class keyword, which is named SimpleClass, and has an id property of type number, and a print function, which just logs a message to the console. Notice anything wrong with this code? Well, the compiler will generate an error message as follows:

error TS2564: Property 'id' has no initializer and is not definitely assigned in the constructor

What this error is indicating is that if we create an instance of this class, then the newly created class will not have the id property initialized, and it will therefore be undefined. If our code is expecting the id property...