I have this class:

class A {
  prop: string
}

and I have this class:

class B extends B {
  prop?: string
}

I am getting this typeScript error:

Property 'prop' in type 'B' is not assignable to the same property in base type 'A'.
  Type 'number | undefined' is not assignable to type 'number'.
    Type 'undefined' is not assignable to type 'number'.ts(2416)

I want to make all of the child class properties that I am inheriting from the parent optional.

So I thought of this solution, create a function that will help TypeScript to understand that.

function OptionalizeParent<T>(cls: T): Partial<T>{
  return cls
}

Then I can use it in the child class like this:

class B extends OptionalizeParent(A) {
  prop?: string
}

But unfortunately, it’s not working, it’s giving me this type of error:

Type 'Partial<typeof A>' is not a constructor function type.

I know this breaks the Liskov substitution principle But I do want to break it because I don’t care about it.