script.js

function removeTransition(e) {
  if(e.propertyName != 'transform') return;
  this.classList.remove('playing');
    
}
function playSoundByKeyCode(keyCode) {
  const audio = document.querySelector(`audio[data-key="${keyCode}"]`);
  const key = document.querySelector(`.key[data-key="${keyCode}"]`);
  
  if(!audio) return;
  audio.currentTime = 0;
  audio.play();
  key.classList.add('playing');
}

function playSound(e) {
  playSoundByKeyCode(e.keyCode);
}


const keys = Array.from(document.querySelectorAll('.key'));
keys.forEach(key => {
  key.addEventListener('transitionend', removeTransition);

  key.addEventListener('click', () => {
    const keyCode = key.getAttribute('data-key');
    playSoundByKeyCode(keyCode)
  })
});

window.addEventListener('keydown', playSound);