Get ID of Parent Element

/*
<ul id="ulOne">
  <li id="liOne">Item A</li>
  <li>Item B</li>
  <li>Item C</li>
</ul>
*/

getParentId("liOne")

function getParentId(idStr) {
    var thisParentId = document.getElementById(idStr).parentElement.id;
    console.log(thisParentId);
  }