Josh Goldberg - Learning TypeScript

If you have an understanding of writing JavaScript code, can run basic commands in a terminal, and are interested in learning about TypeScript, this book is for you.

Maybe youve heard TypeScript can help you write a lot of JavaScript with fewer bugs (true!) or document your code well for other people to read (also true!).Maybe youve seen TypeScript show up in a lot of job postings, or in a new role youre starting.

Whatever your reason, as long as you come in knowing the fundamentals of JavaScript -variables, functions, closures/scope, and classes- this book will take you from no TypeScript knowledge to mastering the fundamentals and most important features of the language.By the end of this book you will understand:

• The history and context for why TypeScript is useful on top of vanilla JavaScript

• How a type system analyzes and understands code

• How to use development-only type annotations to inform the type system

• How TypeScript works with IDEs to provide refactoring tools

And you will be able to:

• Articulate the benefits of TypeScript and general characteristics of its type system

• Add type annotations where useful in your code

• Represent moderately complex types using TypeScripts built-in inferences and new syntax

• Use TypeScript to assist local development in refactoring code

TypeScript is a wildly popular language in both industry and open source:

• GitHubs 2020 State of the Octoverse has it at the 4th top language, up from 7th in 2019 and 2018 and 10th in 2017.

• StackOverflows 2020 Developer Survey has it at the worlds second most loved language (67.1% of users).

• The 2020 State of JS survey has TypeScript at consistently having both high satisfaction and usage amounts as both a build tool and variant of JavaScript.

For frontend developers, TypeScript is well supported in all major UI libraries and frameworks, including Angular -which strongly recommends TypeScript-, Gatsby, Next.js, React, Svelte, and Vue.For backend developers, TypeScript generates JavaScript that runs natively in Node.js; Deno, a similar runtime by Nodes creator, emphasizes first class TypeScript support.

However, despite this plethora of popular project support, I was rather dissapointed by the lack of good introductory content online when I first learned the language.Many of the online documentation sources didnt do a great job of explaining what a type system is or how to use it.They often assumed a great deal of prior knowledge in both JavaScript and strongly typed languages, or were written with only cursory code examples.

Not seeing an OReilly book with a cute animal cover introducing TypeScript was a dissapointment.Im thrilled to be able to spend the time to really make a good, clear introduction to TypeScript for readers who arent already experts in its principles.