How to properly wrap constructors with decorators in TypeScript

Question

The process of wrapping a class with a decorator causes superclasses to be unable to access that classes\' properties. Why?

I have some code that:

1. Crea

Answer 1

A solution using ES2015 Proxy to override the constructor:

function wrap(target: any) {
  return new Proxy(target, {
    construct(clz, args) {
      console.log(`Constructing ${target.name}`);
      return Reflect.construct(clz, args);
    }
  });
}

@wrap
class Base {
  prop: number = 5;
}

class Extended extends Base {
  constructor() {
    super()
  }
}

var a = new Extended()
console.log(new Extended().prop);

You can also run this on StackBlitz