Får inte till sort i kortspelet

let cardHolder = [];
let ul = document.querySelector("ul");
let container = document.getElementById("container");
let deck = [
  {
    id: 1,
    image:
      "https://pixabay.com/get/55e5d0414d4faa0df7c5c10398766263143ad..."
  },
  {
    id: 1,
    image:
      "https://pixabay.com/get/55e5d0414d4faa0df7c5c10398766263143ad..."
  },
  {
    id: 2,
    image:
      "https://pixabay.com/get/57e6d5454a53b10ff3d89938b977692b083ed..."
  },
  {
    id: 2,
    image:
      "https://pixabay.com/get/57e6d5454a53b10ff3d89938b977692b083ed..."
  },
  {
    id: 3,
    image:
      "https://pixabay.com/get/55e3d6464257a514f1dc8460825668204022d..."
  },
  {
    id: 3,
    image:
      "https://pixabay.com/get/55e3d6464257a514f1dc8460825668204022d..."
  },
  {
    id: 4,
    image:
      "https://pixabay.com/get/52e0dc4b4c4faa0df7c5c10398766263143ad..."
  },
  {
    id: 4,
    image:
      "https://pixabay.com/get/52e0dc4b4c4faa0df7c5c10398766263143ad..."
  },
  {
    id: 5,
    image:
      "https://pixabay.com/get/52e0d5474852ad14f1dc8460825668204022d..."
  },
  {
    id: 5,
    image:
      "https://pixabay.com/get/52e0d5474852ad14f1dc8460825668204022d..."
  },
  {
    id: 6,
    image:
      "https://pixabay.com/get/52e4d343435bae14f1dc8460825668204022d..."
  },
  {
    id: 6,
    image:
      "https://pixabay.com/get/52e4d343435bae14f1dc8460825668204022d..."
  },
  {
    id: 7,
    image:
      "https://pixabay.com/get/52e4d04a4d4faa0df7c5c10398766263143ad..."
  },
  {
    id: 7,
    image:
      "https://pixabay.com/get/52e4d04a4d4faa0df7c5c10398766263143ad..."
  },
  {
    id: 8,
    image:
      "https://pixabay.com/get/57e5dc424957b10ff3d89938b977692b083ed..."
  },
  {
    id: 8,
    image:
      "https://pixabay.com/get/57e5dc424957b10ff3d89938b977692b083ed..."
  }
];

function render() {
  deck.forEach(carditem => {
    let card = document.createElement("li");
    card.innerHTML = `
    <div class="flip-card">
  <div class="flip-card-inner">
    <div class="flip-card-front" id="${carditem.id}"></div>
    <div class="flip-card-back">
    <img src="${carditem.image}" class="img">
    </div>
  </div>
</div>
    `;
    card.id = carditem.id;
    ul.appendChild(card);
  });
}

// Shuffle
function shuffle(a) {
  for (let i = a.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [a[i], a[j]] = [a[j], a[i]];
  }
  return a;
}

function check() {
  if (cardHolder.length === 2) {
    let isMatch = cardHolder[0] === cardHolder[1];
    isMatch ? console.log("vinn") : console.log("loss");
    cardHolder = [];
  }
}
container.addEventListener("click", function(e) {
  e.target.parentNode.classList.add("active-img");
  cardHolder.push(e.target.id);

shuffle(deck);
render();