How to correctly describe the interface for checking method arguments in TS?

Question

typescript

There is an interface IFoo and a class Foo

interface IFoo {
  bar(value: number): number;
}

class Foo implements IFoo {
  bar(num) {
    return num * num;
  }
}

Despite the fact that both the method and its argument are described in the interface, nevertheless, the num argument is highlighted as any

Playground where you can see the actual example

Question: how to correctly describe the interface so that the argument is highlighted correctly?

Answer 1

No way. Unfortunately, you must explicitly declare the types of the arguments. Ts can only help you if the type in the class is incompatible with the type in the interface.