Discussion on: TypeScript: type vs interface

let suits = ["hearts", "spades", "clubs", "diamonds"];

function pickCard(x: {suit: string; card: number; }[]): number;
function pickCard(x: number): {suit: string; card: number; };
function pickCard(x: any): any {
    // Check to see if we're working with an object/array
    // if so, they gave us the deck and we'll pick the card
    if (typeof x == "object") {
        let pickedCard = Math.floor(Math.random() * x.length);
        return pickedCard;
    }
    // Otherwise just let them pick the card
    else if (typeof x == "number") {
        let pickedSuit = Math.floor(x / 13);
        return { suit: suits[pickedSuit], card: x % 13 };
    }
}

interface IPickCard {
    (x: {suit: string; card: number; }[]): number
    (x: number): {suit: string; card: number; }
}

type PickCard = 
  | ((x: {suit: string; card: number; }[]) => number)
  | ((x: number) => {suit: string; card: number; });

const y: PickCard = pickCard;
const x: IPickCard = pickCard;