Decorators

• Modify different properties,methods and accessors in a class
• Not equal to JS decorators
• Inside classes ONLY
• "experimentalDecorators": true and "emitDecoratorMetadata": true must be enabled in tsconfig.json
• It is executed only ONE time when class is created and not when it is instantiated

function logError(target: any, key: string, desc: PropertyDescriptor): void {
  console.log(target); // Prototype of the class (properties won't appear because they are created in the constructor). Prototype only stores methods definitions
  console.log(key); // key of the class: method, property or accessor
  console.log(desc); // property descriptions (Object.getOwnPropertyDescriptor)
}

• When a decorator is wrapper inside of a function it's called a Decorator factory
• It allows additional arguments to be passed