Design Patterns in TypeScript

"Design Patterns in TypeScript" is a practical guide to applying classic design patterns (GoF) in the modern TypeScript ecosystem. The book doesn't just list abstract diagrams but shows how each pattern is implemented with strict typing, generics, the module system, and ECMAScript features.

Who this book is for:

• Developers who are already familiar with the basics of TypeScript and want to take their code quality to the next level.
• Backend and frontend engineers working with Angular, React, Node.js, or any other TypeScript frameworks.
• Programmers transitioning from JavaScript to TypeScript who want to master "correct" architectural techniques.
• Students and practicing professionals preparing for interviews where patterns are often asked about.

What you will learn from the book:

• How to use creational patterns (Singleton, Factory, Builder, Prototype) for flexible object creation without binding to specific classes.
• How structural patterns (Adapter, Decorator, Proxy, Facade) help organize connections between components and adapt old code to new requirements.
• How behavioral patterns (Observer, Strategy, State, Command) make system behavior predictable, extensible, and easily modifiable.
• How TypeScript-specific features (utility types, conditional types, mapped types) allow creating even safer and more elegant pattern implementations.
• Real-world examples from practice: from simple utilities to the architecture of entire applications.

Book features:

• Each pattern comes with complete TypeScript code, ready to use.
• Detailed comments and type analysis — you will understand why a particular design was chosen.
• Comparison of classic implementation with the "typed" version — you will see how TypeScript improves patterns.
• Practical exercises and self-test questions at the end of each chapter.
• Tips on integrating patterns into existing projects without rewriting all the code.

This book is not about dry theory — it is about making your TypeScript code reliable, readable, and ready for change. Whether you are building a microservice, a complex interface, or a library, the patterns from this book will become your reliable tool.