HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>String.at()</title>
</head>
<body>
  <pre id="out"></pre>
  <script>
    function returnLast(str) {
      return str.at(-1);
    }
    document.getElementById("out").textContent =
      returnLast("my-invoice01") + "\n" + returnLast("my-invoice02");
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

String.at() — last character (Try It)