Design Patterns in TypeScript

The book "Design Patterns in TypeScript" is a practical guide to applying classic and modern design patterns (GoF) in the TypeScript environment. Unlike abstract descriptions in Java or C++, the author emphasizes TypeScript's strengths: strong typing, interfaces, generics, decorators, and a modular system. You will learn to write code that is easy to maintain, test, and extend.

What you will learn from the book:

• Fundamentals of SOLID and GRASP — how object-oriented design principles help avoid "spaghetti code".
• Creational Patterns (Singleton, Factory, Builder, Prototype) — creating objects without tight coupling to specific classes.
• Structural Patterns (Adapter, Decorator, Facade, Proxy) — organizing classes and objects into flexible hierarchies.
• Behavioral Patterns (Observer, Strategy, Command, State, Chain of Responsibility) — managing interaction between objects.
• Advanced Techniques — using generics, conditional types, and mapped types to create type-safe implementations.
• Real-World Cases — integrating patterns with frameworks (React, Express, NestJS) and testing with Jest.

Who this book is for:

• Developers transitioning from JavaScript to TypeScript who want to write architecturally clean code.
• Backend and frontend specialists looking to systematize their knowledge of design.
• Team leads and architects seeking ready-made templates for building scalable applications.

Each pattern is accompanied by a step-by-step breakdown: from problem statement to implementation in TypeScript, taking static typing into account. At the end of each chapter, there are exercises with answers for self-assessment. The book is suitable both for learning from scratch and as a quick reference.

Make your code reliable and predictable — master design patterns in TypeScript!