Build a Logger and Validator with TypeScript Decorators (Like NestJS)

Note: This post is a translated version of an article originally published on my personal blog. You can read the original Korean post here . What Are Decorators? Decorators are a metaprogramming syntax that lets you attach metadata — or extend behavior — on classes, methods, properties, and parameters without modifying the original code . They're commonly used for: Logging — track when methods are called Validation — enforce constraints on class properties Dependency Injection — wire up services