<ul class="drum">
 <li>A</li>
 <li>S</li>
 <li>D</li>
</ul>

const Olist = document.querySelectorAll('.drum li');
  for(let i = 0; i < Olist.length; i++){
    Olist[i].addEventListener('click', function(e){
        console.log(`I was clicked ${Olist[i]}`);
    })
 }