To get the most out of this book

• You will need the TypeScript compiler and an editor of some sort. The TypeScript compiler is available on Windows, MacOS, and Linux as a Node plugin. Chapter 1, Up and Running Quickly, describes the setup of a development environment
• This book has been designed in a "type as you read" format. The code snippets are small, so feel free to type out the code yourself, as the text progresses, and learn by building up your code base and knowledge as you go.

Download the example code files

The code bundle for the book is hosted on GitHub at https://github.com/PacktPublishing/Mastering-TypeScript-Fourth-Edition. We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

Download the color images

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://static.packt-cdn.com/downloads/9781800564732_ColorImages.pdf.

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. For example: "We can configure webpack using the webpack.config.js file."

A block of code is set as follows:

class MyClass {
    add(x: number, y: number) {
      return x + y;
   }
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are highlighted:

const modulus: Observable<number> = emitter.pipe(
    map((value: number) => {
        console.log(`received : ${value}`);
        return value % 2;
    }));

Any command-line input or output is written as follows:

npm install @types/express

Bold: Indicates a new term, an important word, or words that you see on the screen, for example, in menus or dialog boxes, also appear in the text like this. For example: "Select Run from the Debug panel."