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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>before callback demo</title>
  <style>
    body { font-family: sans-serif; padding: 16px; max-width: 480px; }
    p { background: #dbeafe; margin: 8px 0; padding: 8px 10px; border-radius: 4px; }
    b { color: #1d4ed8; display: block; margin: 4px 0 8px; }
    button { margin-top: 12px; padding: 10px 16px; background: #2563eb; color: #fff; border: none; border-radius: 6px; cursor: pointer; }
    #hint { color: #64748b; font-size: 14px; margin-top: 10px; }
  </style>
</head>
<body>
  <p class="intro">First paragraph</p>
  <p class="note">Second paragraph</p>
  <button type="button">Before callback badges</button>
  <p id="hint">Callback inserts &lt;b&gt; sibling showing each p's className.</p>
  <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
  <script>
    $("button").on("click", function() {
      $("p").not("#hint").before(function() {
        return "<b>" + this.className + "</b>";
      });
      $("#hint").text("Each paragraph now has a <b> sibling above showing its class.");
    });
  </script>
</body>
</html>

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jQuery .before() — callback with className (Try It)