Book Image

The TypeScript Workshop

By : Ben Grynhaus, Jordan Hudgens, Rayon Hunte, Matt Morgan, Vekoslav Stefanovski
5 (1)
Book Image

The TypeScript Workshop

5 (1)
By: Ben Grynhaus, Jordan Hudgens, Rayon Hunte, Matt Morgan, Vekoslav Stefanovski

Overview of this book

By learning TypeScript, you can start writing cleaner, more readable code that’s easier to understand and less likely to contain bugs. What’s not to like? It’s certainly an appealing prospect, but learning a new language can be challenging, and it’s not always easy to know where to begin. This book is the perfect place to start. It provides the ideal platform for JavaScript programmers to practice writing eloquent, productive TypeScript code. Unlike many theory-heavy books, The TypeScript Workshop balances clear explanations with opportunities for hands-on practice. You’ll quickly be up and running building functional websites, without having to wade through pages and pages of history and dull, dry fluff. Guided exercises clearly demonstrate how key concepts are used in the real world, and each chapter is rounded off with an activity that challenges you to apply your new knowledge in the context of a realistic scenario. Whether you’re a hobbyist eager to get cracking on your next project, or a professional developer looking to unlock your next promotion, pick up a copy and make a start! Whatever your motivation, by the end of this book, you’ll have the confidence and understanding to make it happen with TypeScript.
Table of Contents (16 chapters)
Preface

Union Types

Union Types are similar to intersections as they are a combination of types to form a single type. Union types differ, however, in that they do not merge your types but provide or type functionality instead of an and type functionality, which was the case with intersection types. This works in a similar way to the ternary operator in JavaScript, where the types you are combining are separated by the | pipe. If this is confusing, it will all become clear as we move on to an example. We will also take a look at type guards, which is a pattern that will play a major role in the app use of union types. First, consider the following visual representation of a union type:

Figure 6.7: Illustration of a union type assignment

In the preceding diagram, we have a basic diagram of a union type assignment, where Age can be of the number or string datatypes. You can have union types with more than two options and non-primitive types. This gives you the option...