let deck = [];
let suits = ["hearts", "diamonds", "spades", "clubs"];
let values = ["ace", "2", "3", "4", "5", "6", "7", "8", "9", "10", "jack", "queen", "king"];

for (let suit of suits) {
  for (let value of values) {
    deck.push(value + " of " + suit);
  }
}

function shuffleDeck(deck) {
  for (let i = deck.length - 1; i > 0; i--) {
    let j = Math.floor(Math.random() * (i + 1));
    [deck[i], deck[j]] = [deck[j], deck[i]];
  }
  return deck;
}

console.log(shuffleDeck(deck));