JavaScript (Node.js) Application Architecture

This book is a comprehensive guide to designing and developing scalable, fault-tolerant, and maintainable applications on Node.js. It is not about language syntax or basic platform capabilities, but about how to organize code, choose the right architecture, and avoid typical mistakes that turn a project into a "big ball of mud."

The author, with many years of experience in building high-load systems, shares proven practices and real-world cases. You will learn how to transition from a simple monolithic application to a flexible modular system ready for increased load and changing requirements.

What you will learn from the book:

• Fundamental principles: SOLID, KISS, DRY, YAGNI and their application in the context of JavaScript.
• Layered architecture: separation into controllers, services, repositories, and middleware.
• Design patterns: Observer, Factory, Singleton, Module, Dependency Injection, and others adapted for Node.js.
• Working with asynchrony: managing promises, async/await, streams, EventEmitter.
• API design: REST, GraphQL, versioning, pagination, error handling.
• Microservices: decomposition strategies, inter-service communication (RabbitMQ, NATS, HTTP/gRPC), orchestration and choreography.
• Databases: choosing between SQL and NoSQL, working with transactions, replication, sharding.
• Testing: unit, integration, e2e testing. Tools: Jest, Mocha, Supertest.
• CI/CD and DevOps: containerization (Docker), orchestration (Kubernetes), monitoring (Prometheus, Grafana), logging.
• Security: protection against XSS, CSRF, SQL injections, secret management, authentication (JWT, OAuth2).

Who this book is for:

• Backend developers on Node.js with 1+ years of experience who want to level up.
• Team Leads and architects looking for a systematic approach to building applications.
• Developers planning to migrate from a monolith to microservices.
• Anyone tired of "spaghetti code" and wanting to build reliable systems.

The book contains numerous code listings, diagrams, and checklists. All examples are based on real projects and are ready for use. After reading, you will be able to confidently design architecture, make informed technical decisions, and build applications that can withstand any load.

This is not just a book — it is a desktop reference for those who take the quality of their code and career growth seriously.