色変わり石

#stone {
  width: 100px;
  height: 100px;
  background: red;
  cursor: pointer;
  transition: background 0.3s;
}

const stone = document.querySelector('#stone');
let isRed = true;

stone.addEventListener('click', function() {
  if (isRed) {
    stone.style.background = 'green';
    isRed = false;
  } else {
    stone.style.background = 'orange';
    isRed = true;
  }
});