HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>removeAttribute simpler</title>
  <style>
    #box { padding: 12px; border: 1px solid #ccc; margin: 8px 0; }
  </style>
</head>
<body>
  <div id="box" data-role="primary">Plain HTML attribute</div>
  <button type="button" id="btn">removeAttribute('data-role')</button>
  <pre id="out">—</pre>
  <script>
    document.getElementById("btn").addEventListener("click", function () {
      var el = document.getElementById("box");
      el.removeAttribute("data-role");
      document.getElementById("out").textContent =
        "hasAttribute data-role: " + el.hasAttribute("data-role");
    });
  </script>
</body>
</html>

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removeAttributeNS vs removeAttribute (Try It)