<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Alert Box</title>
</head>
<body>
<h1>Hello JavaScript...</h1>
<h3>
This is for testing the alert message in JavaScript.
</h3>
<script>
alert("Alert message using JavaScript.");
</script>
</body>
</html>