NestJS Dependency Injection Master NestJS dependency injection for building modular, testable Node.js applications with proper service architecture, provider patterns, and module organization. Table of Contents - Provider Patterns - Module System - Injection Scopes - Advanced Patterns - Best Practices - Common Pitfalls - Resources Provider Patterns Class Providers (Standard Pattern) Value Providers Factory Providers Async Providers with useFactory Token-Based Injection with String Tokens Token-Based Injection with Symbol Tokens Optional Dependencies with @Optional() Property-Based Injection C…