Edit in JSFiddle

const uiTag = document.getElementById("parent-list");
uiTag.addEventListener("click", (e) => { alert(e.target.id); });

<ul id="parent-list">
  <li id="id1">Item 1</li>
  <li id="id2">Item 2</li>
  <li id="id3">Item 3</li>
  <li id="id4">Item 4</li>
  <li id="id5">Item 5</li>
  <li id="id6">Item 6</li>
</ul>