Copying information at the click of a button-CodePudding

Script that copies information on button click and then returns the original text loses some of the button's content.

missing icon from Font Avesome. Can this be fixed somehow?

I'm a newbie, I'll be glad for a detailed answer.

html:

<p id="battlenet-id">gameid#26737</p>
<p id="xbox-id">gameid#5423</p>

<li><a href="javascript:void(0);"  onclick="copyToClipboard('battlenet-id', this)"><i ></i> Battle.net</a></li>
<li><a href="javascript:void(0);"  onclick="copyToClipboard('xbox-id', this);"><i ></i> Xbox</a></li>

function copyToClipboard(elementId, thisButton) {
  let oldText = thisButton.textContent
  thisButton.textContent = '!Copied!'
  const timeout = setTimeout(function() { thisButton.textContent = oldText }, 3000);
  var aux = document.createElement("input");
  aux.setAttribute("value", document.getElementById(elementId).innerHTML);
  document.body.appendChild(aux);
  aux.select();
  document.execCommand("copy");
  console.log("