Refactoring JavaScript (Node.js) Code

The book "Refactoring JavaScript (Node.js) Code" is a practical guide for developers who want to transform their code from "working" to "ideal." Unlike many abstract books on refactoring, this book is entirely focused on the JavaScript and Node.js ecosystem, addressing real-world problems faced by backend and full-stack application developers.

The author, Alexey Petrov, a senior developer with 10 years of experience, has compiled a collection of the most common "code smells" in Node.js projects and offers step-by-step techniques for eliminating them.

Who is this book for?

• For middle and senior developers who want to systematize their knowledge of refactoring.
• For team leads who conduct code reviews and want to make reasoned suggestions for improvements.
• For developers transitioning from other languages to JavaScript who want to write idiomatic code.
• For those working on legacy Node.js projects and seeking safe ways to modernize them.

What you will learn from the book:

• How to identify problematic code areas: from monster functions to improper error handling.
• Safe refactoring techniques for asynchronous code (Promises, async/await, callback hell).
• How to properly break monolithic modules into loosely coupled components.
• Refactoring patterns for Express.js, Koa, and other frameworks.
• Performance improvements: optimizing loops, closures, and memory management.
• Testing methods during refactoring: how to avoid breaking existing functionality.
• Working with TypeScript: how to add types to an existing JavaScript project.

Each chapter contains "before" and "after" code examples, as well as self-check checklists. You will learn not just to rewrite code, but to make architectural decisions that will make your codebase resilient to change and scaling.

This book will become your desktop reference for writing clean, maintainable, and performant code in JavaScript and Node.js.