HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>createCDATASection forbidden sequence</title>
  <style>body{font-family:system-ui,sans-serif;padding:1.5rem;} pre{border:1px solid #ccc;padding:0.75rem;}</style>
</head>
<body>
  <button id="btn">Pass bad ]]> sequence</button>
  <pre id="out"></pre>
  <script>
    document.getElementById("btn").addEventListener("click", function () {
      var doc = new DOMParser().parseFromString("<root/>", "application/xml");
      try {
        doc.createCDATASection("bad ]]> sequence");
        document.getElementById("out").textContent = "No error (unexpected)";
      } catch (err) {
        document.getElementById("out").textContent = err.name + "\n" + err.message;
      }
    });
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

Document.createCDATASection — forbidden ]]> (Try It)