HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>getAttributeNames list</title>
</head>
<body>
  <div id="card" class="panel" data-id="42" data-role="main">Card</div>
  <pre id="out"></pre>
  <script>
    var card = document.getElementById("card");
    document.getElementById("out").textContent =
      JSON.stringify(card.getAttributeNames().sort());
  </script>
</body>
</html>

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Element.getAttributeNames — list names (Try It)