I'm new at JS
I'm making a drum kit website and i create a switch section but it's not working.
var numberOfDrumButtons = document.querySelectorAll(".drum").length;
for (var i = 0; i < numberOfDrumButtons; i++) {
  document.querySelectorAll(".drum")[i].addEventListener("click", function() {
    var buttonInnerHtml = this.innerHTML;
    switch (buttonInnerHtml) {
      case "w":
        var tom1 = new Audio('songs/oni-chan.mp3');
        tom1.play();
        break;
      case "a":
        var tom2 = new Audio('songs/oni-chan2.mp3');
        tom2.play();
        break;
      case "s":
        var tom3 = new Audio('songs/oni-chan3.mp3');
        tom3.play();
        break;
      default:
        break;
    }
  })
}    
    
HTML:
  <div class="set">
    <button class="w drum"><span>w</span></button>
    <button class="a drum"><span>a</span></button>
    <button class="s drum"><span>s</span></button>
    <button class="d drum"><span>d</span></button>
    <button class="j drum"><span>j</span></button>
    <button class="k drum"><span>k</span></button>
    <button class="l drum"><span>L</span></button>
  </div>
  <script src="index.js" href="UTF-8"></script>
 
     
    