Decorators
TypeScript decorators provide a powerful system for annotating class definitions to observe and modify their functionality.
A decorator definition is a special function used to annotate some aspect of the class definition. By inserting the function name, preceded by an @ character, the function is called when the class is loaded. You can use decorators to gain full access to the initialization logic, object properties, instance methods, and even method parameters of a class definition.
Class decorators
With decorator functions, you can take complete control over how a class declaration works. Notice in the example below that the classDecorator
function is called before any instances of the class are created.
A common pattern for using decorators is to provide a decorator factory function, which produces a function whose type matches the global
utility type ClassDecorator.
Accessor decorator
Method decorators
A method decorator is used to annotate a method declaration.