​

let upgradeCost = 10;

​

const scoreDisplay = document.getElementById("score");

​

const clickArea = document.getElementById("click-area");

​

const upgradeBtn = document.getElementById("upgrade-btn");

​

clickArea.addEventListener("click", () => {

  score++;

​

  scoreDisplay.innerText = `Score: ${score}`;

});

​

upgradeBtn.addEventListener("click", () => {

  if (score >= upgradeCost) {

    score -= upgradeCost;

​

    upgradeCost *= 2; // Increase cost for the next upgrade

​

    upgradeBtn.innerText = `Upgrade (Cost: ${upgradeCost})`;

​

    scoreDisplay.innerText = `Score: ${score}`;

  } else {

    alert("Not enough points!");

  }

});

​