hero.ts

export class Hero {
  id: number;
  name: string;
  superpower: Power;
  friends: Hero[];
}

export class Power {
  name: string;
}

like.ts

// TODO: add conditional type for arrays (meaning when T[K] is an array) (requires TS 2.8, planned for NG 6.1)
// until then, simply do a manual cast from `Like<T[K][]>` to `Like<T[K]>[]`
export type Like<T> = {
  [K in keyof T]: T[K] | Like<T[K]>
};

oldway.ts

// This is how we used to write TypeScript
// Declare anonymous objects as Hero
const windstorm: Hero = {
  id: 1,
  name: 'Windstorm',
  superpower: {
    name: 'Storm manipulation'
  },
  friends: [
    { ... },
    { ... },
    { ... }
  ]
};

// Now you get the following intellisense
// windstorm: Hero
// windstorm.id: number;
// windstorm.name: string;
// windstorm.superpower: Power;
// windstorm.superpower.name: string;
// windstorm.friends: Hero[];

// but these are lies: windstorm's prototype is actually Object, not Hero
const isHero = windstorm instanceof Hero; // false

// same for superpower
const isPower = windstorm.superpower instanceof Power; // false
    
// same for friends
const areHeroes = windstorm.friends.every(friend => friend instanceof Hero); // false, false, false

usingLike.ts

// This is how I write TypeScript now
// Declare anonymous objects as Like<Hero> instead of Hero
const windstorm: Like<Hero> = {
  id: 1,
  name: 'Windstorm',
  superpower: {
    name: 'Storm manipulation'
  },
  friends: [
    { ... },
    { ... },
    { ... }
  ]
};

// Now you get the following intellisense
// windstorm: Like<Hero>
// windstorm.id: number;
// windstorm.name: string;
// windstorm.superpower: Power | Like<Power>;
// windstorm.superpower.name: string;
// windstorm.friends: Hero[] | Like<Hero[]>;

// instanceof Hero is still false, but this time you would have expected that, because intellisense
const isHero = windstorm instanceof Hero; // false, but not unexpected

// same for superpower
const isPower = windstorm.superpower instanceof Power; // false, but not unexpected
    
// same for friends
const areHeroes = windstorm.friends.every(friend => friend instanceof Hero); // false, false, false
    
// The only problem right now: TS <2.8 doesn't have conditional types
// ideally we would want `friends` to be typed like this:

// windstorm.friends: Hero[] | Like<Hero>[];

// this should be possible starting with TS 2.8 but I'm waiting for NG 6.1 to make it happen