W3Schools Tryit Editor

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Bootstrap Example</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
</head>
<body>

<div class="container">
  <h2>Alert Events</h2>
  <p>The <strong>closed</strong> event occurs when the alert message has been closed.</p>
  <div class="alert alert-danger alert-dismissible" id="myAlert">
    <a href="#" class="close">&times;</a>
    <strong>Hey you!</strong> Try to close this alert message.
  </div>
</div>

</body>
</html>