Validate Custom class/type in Javascript

Question

I have created a class like below,

export class MusicAlbumAvailability {
  [albumName: string]: string;
}

And I have a function written like below,

function(album: MusicAlbumAvailability) {
  console.log("Album: ", album)
}

Now, how do I validate that the value passed here is valid MusicAlbumAvailability? Because I can still call this function using {"key1":"value1"} and {"key1":1}

I tried validating using instanceof but returns the same response for both the input