Node.js Design Patterns
📌 Covered in this chapter:
MVC · Repository Pattern · Factory & Singleton · Observer Pattern · Dependency Injection
Recognize and apply common software design patterns in a Node.js context: MVC, Repository, Factory, Singleton, and more.
1Node.js Design Patterns — What You'll Learn
Recognize and apply common software design patterns in a Node.js context: MVC, Repository, Factory, Singleton, and more.
Here's everything this chapter covers, in the order you'll learn it:
- MVC (Model-View-Controller)
- The Repository pattern
- The Service pattern
- The Factory pattern
- The Singleton pattern
- The Adapter pattern
- The Strategy pattern
- The Observer pattern (Node's EventEmitter is a real-world example)
- Dependency injection
- Event-driven design
- Knowing when NOT to use a pattern
2Working Example
💻 Example: Node.js Design Patterns
JavaScript
▶ Run in Compiler
import { EventEmitter } from "node:events";
const orderEvents = new EventEmitter();
orderEvents.on("order:created", (order) => {
console.log("Sending confirmation email for order", order.id);
});
orderEvents.emit("order:created", { id: 101 });3Best Practices & Common Pitfalls
💡 Key things to remember:
- Design patterns are tools, not requirements — apply one only when it genuinely simplifies your code; forcing a pattern where a plain function would do adds unnecessary complexity.
❓ Frequently Asked Questions (FAQ)
Q What's the most important thing to understand about node.js design patterns?
Focus on: MVC · Repository Pattern · Factory & Singleton · Observer Pattern · Dependency Injection. These are the core building blocks this chapter's examples are built around, and they show up repeatedly in later chapters of this course.
Q Do I need external npm packages for node.js design patterns?
Only where explicitly shown in the code examples above (like Express, Zod, or Socket.IO) — otherwise, this chapter relies entirely on Node.js's own built-in capabilities.