Advanced TypeScript
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Advanced TypeScript

About the Book

The book introduces you to the world of advanced TypeScript concepts including: compiler flags for catching more errors, generic types, and how to compose types with discriminated unions. 

After reading this book, you’ll feel more confident in your TypeScript skills. You will be able to write types that detect whole classes of possible runtime errors at compile time. Typing even the most untypeable JavaScript code will be a no brainer for you, and you’ll be fluent in TypeScript error messages.

The course is divided into five chapters. All of them have real life examples and focus on practicality. The first module is dedicated to strict typing. It discusses the most important compiler flags responsible for increasing strictness of type checking. The second module talks about one of the most confusing concepts of TypeScript, generic types. The third module is the most important one as it explains how to compose types in TypeScript and focuses on discriminated union types. The fourth module lists other advanced types available in TypeScript and explains their usefulness. Finally, the fifth module is specifically dedicated to real-life examples of using TypeScript in complex scenarios. It talks about debugging compile errors and about using TypeScript with some of the most popular libraries.

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About the Author

Miłosz Piechocki
Miłosz Piechocki

I'm an experienced software engineer, currently working as an Engineering Manager at a SaaS company. I've been using TypeScript for the last 5 years. Previously, I wrote code in various statically typed languages, including C#, Haskell and Scala. I run a programming blog and love to share knowledge at meet-ups and conferences.

Table of Contents

  • Introduction
  • Strict Types
    • Introduction
    • No Implicit any
    • Fixing noImplicitAny Errors
    • The unknown Type
    • Strict Null Checks
    • Optionality
    • Strict Property Initialization
    • Non-Null Assertion Operator
    • Exercise in Strictness
  • Generics
    • Introduction
    • Function Types
    • Generic Functions
    • Generic Functions Example - Typing reduce
    • Generic Interfaces - OOP Perspective
    • Generic Interfaces - FP Perspective
    • Type Argument Constraints
    • Type Constructors
    • Type Argument Propagation
  • Composing Types
    • Introduction
    • Union and Intersection Types
    • Discriminated Union Types
    • Discriminated Unions in Practice
    • State Machines
    • Discriminated Unions vs Subtyping
  • Advanced Types
    • Introduction
    • Conditional Types Introduction
    • Built-in Conditional Types
    • The infer Keyword
    • Conditional Types Example - React Component Props
    • Mapped Types Introduction
    • Built-in Mapped Types
    • Type Guards
    • Custom Type Guards
    • Nominal Types
  • TypeScript in Practice
    • Introduction
    • Debugging Errors: Type Assignability
    • Debugging Errors: Narrowing Types
    • Debugging Errors: Unintuitive Error Message
    • React and TypeScript: useState Hook
    • React and TypeScript: useReducer Hook
  • Conclusion

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