Typescript: define interface without specific keys & chain objects

Question

I have such example of data, that I receive:

{
  Europe: {
    WestEurope: {
      Belgium: [French, English, Dutch]
   }
  }
}

Not sure how I can create an interface for such a dynamic structure, where I have a tree:

Object->Object(of Regions)->Object(of SubRegions)->Object(of Countries)->ArrayOfStrings(of languages)

I tried so:

export interface Localisation {
    [key: string]: Localisation;
}
export interface Region {
    [key: string]: Region;
}
export interface SubRegion {
    [key: string]: SubRegion;
}
export interface Country {
    [key: string]: Country;
}
export interface Language {
    [index: number]: Array<string>;
}

but they aren't 'chained' -> so 'Localisation' doesn't know that it contains 'Regions' etc. And I want to connect them somehow. Is it possible?

Answer 1

How about this?

interface Country {
  [proporty: string]: string[];
}

interface SubRegion {
  [property: string]: Country;
}

interface Region {
  [property: string]: SubRegion;   
}

interface Localisation {
  [property: string]: Region;
}

Answer 2

An alternative is not to use separate interfaces, but nest everything under one interface. This only works if you don't need the separate types though.

interface Localization {
    [region: string]: {
        [subregion: string]: {
            [country: string]: string[]
        }
    }
}


// Usage

const data: Localization = {
    Europe: {
        WestEurope: {
            Belgium: ['French', 'English', 'Dutch']
        }
    }
};

const westEurope = data['Europe']['WestEurope']; // Is of type { [country: string]: string[] }