Learning Typescript: Enhance Your Web Development Skills Using Type-Safe JavaScript (Paperback)

TypeScript has conquered the world of JavaScript: it's one of the world's fastest growing and most popular languages across developer surveys, widely used in consumer and business companies alike, and frequently credited for helping massive web applications scale. But what is TypeScript? How does it work, why does it work, and how can we use it?

Learning TypeScript takes beginner to intermediate JavaScript programmers from knowing nothing about types or a type system to full mastery of the fundamentals of TypeScript. It's more than a means to find bugs and typos--it's a useful system for declaring the way our JavaScript should work and helping us stick to it. You'll learn how TypeScript:

• interacts with JavaScript
• analyzes and understands code
• augments your existing development pattern
• helps you document your code
• works with IDEs to provide refactoring tools
• assists local development in refactoring code
• helps you develop more quickly with fewer bugs

Who Should Read This Book

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 you’ve 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 you’ve seen TypeScript show up in a lot of job postings, or in a new role you’re 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 models code
• How a type checker analyzes code
• How to use development-only type annotations to inform the type system
• How TypeScript works with IDEs (Integrated Development Environments) to provide code exploration and 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 TypeScript’s built-in inferences and new syntax.

Navigating this Book

Learning TypeScript has two purposes:

• You can read through it once to understand TypeScript as a whole.
• Later, you can refer back to it as a practical introductory TypeScript language reference.

This book ramps up from concepts to practical use across three general sections:

• Part I, “Concepts”: How JavaScript came to be, what TypeScript adds to it, and the foundations of a type system as TypeScript creates it.
• Part II, “Features”: Fleshing out how the type system interacts with the major parts of JavaScript you’d work with when writing TypeScript code.
• Part III, “Usage”: Now that you understand the features that make up the TypeScript language, how to use them in real-world situations to improve your code reading and editing experience.

TypeScript已征服了JavaScript的世界：根據開發者調查，它是全球增長最快且最受歡迎的語言之一，廣泛應用於消費者和企業公司，並經常被認為有助於大型網絡應用的擴展。但是TypeScript是什麼？它是如何工作的？為什麼它能工作？我們如何使用它？

《學習TypeScript》將初學者和中級JavaScript程序員從對類型或類型系統一無所知，帶領他們全面掌握TypeScript的基礎知識。它不僅僅是一種查找錯誤和拼寫錯誤的手段，它還是一個有用的系統，用於聲明我們JavaScript應該如何工作並幫助我們遵循它。您將學習到TypeScript的以下功能：

- 與JavaScript的交互
- 分析和理解代碼
- 增強現有的開發模式
- 幫助您記錄代碼
- 與IDE一起提供重構工具
- 幫助您在本地開發中重構代碼
- 幫助您更快地開發，減少錯誤

適合閱讀本書的讀者：

如果您了解如何編寫JavaScript代碼，可以在終端運行基本命令，並且有興趣學習TypeScript，那麼本書適合您。也許您聽說過TypeScript可以幫助您以更少的錯誤編寫大量的JavaScript（是真的！），或者為其他人閱讀您的代碼提供良好的文檔（也是真的！）。也許您在許多工作職位中看到了TypeScript的身影，或者您正在開始一個新的角色。無論出於何種原因，只要您具備JavaScript的基礎知識（變量，函數，閉包/作用域和類），本書將帶您從對TypeScript一無所知到掌握該語言的基礎知識和最重要的功能。

通過閱讀本書，您將了解：

- TypeScript在“原始”JavaScript之上有用的歷史和背景
- 類型系統如何模擬代碼
- 類型檢查器如何分析代碼
- 如何使用僅在開發中的類型註釋通知類型系統
- TypeScript如何與IDE（集成開發環境）一起提供代碼探索和重構工具

您將能夠：

- 闡述TypeScript的好處以及其類型系統的一般特性
- 在代碼中有用的地方添加類型註釋
- 使用TypeScript的內置推斷和新語法表示中等複雜的類型

本書的導航：

《學習TypeScript》有兩個目的：

- 您可以通讀一遍，全面了解TypeScript。
- 以後，您可以將其作為實用的入門TypeScript語言參考資料。

本書分為三個主要部分，從概念到實際應用：

- 第一部分：“概念”：JavaScript的發展歷程，TypeScript對其的增強以及TypeScript創建的類型系統的基礎知識。
- 第二部分：“功能”：深入了解類型系統與編寫TypeScript代碼時涉及的主要JavaScript部分的交互。
- 第三部分：“用法”：現在您了解了構成TypeScript語言的功能，您將學習如何在實際情況下使用它們，以改進代碼閱讀和編輯體驗。

Josh Goldberg is a frontend developer from New York with a passion for open source, static analysis, and the web. He is a full-time open-source maintainer who contributes regularly to TypeScript and open-source projects in its ecosystem, such as typescript-eslint and TypeStat. His past work includes spearheading Codecademy's usage of TypeScript, helping create its Learn TypeScript course, and architecting rich client applications at Microsoft. His projects range from static analysis to meta-languages to re-creating retro games in the browser. Also cats.

Josh Goldberg是來自紐約的前端開發人員，對於開源、靜態分析和網頁開發充滿熱情。他是一位全職的開源維護者，定期為TypeScript和其生態系統中的開源項目（如typescript-eslint和TypeStat）做出貢獻。他過去的工作包括帶領Codecademy在使用TypeScript方面，幫助創建其Learn TypeScript課程，以及在Microsoft架構豐富的客戶端應用程序。他的項目範圍從靜態分析到元語言，再到在瀏覽器中重新創建復古遊戲。還有貓。