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The TypeScript Workshop

The TypeScript Workshop

By : Ben Grynhaus , Jordan Hudgens , Rayon Hunte , Matt Morgan , Wekoslav Stefanovski
4.7 (19)
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The TypeScript Workshop

The TypeScript Workshop

4.7 (19)
By: Ben Grynhaus , Jordan Hudgens , Rayon Hunte , Matt Morgan , Wekoslav 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)
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Preface

Anatomy of a Promise

A promise is a JavaScript object that can exist in three states: pending, fulfilled, or rejected. Although promises can be instantly fulfilled or rejected, it is most typical for a promise to be created in a pending state and then resolved to be fulfilled or rejected as an operation succeeds or fails. Promises are chainable and implement several convenience methods that we'll go into.

To understand the states of a promise better, it's important to know that the states of a promise cannot be queried. As a programmer, we do not check the state of the promise and take action based on that state. Rather we provide a function callback that will be invoked when the promise reaches that state. For example, we make an HTTP request to our backend server and get a promise in response. Now we have set up our event and we merely need to tell the promise what to do next and how to handle any errors. Examples of this will follow.

The Promise Callback

A promise...

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