how to inject javascript into html
<!DOCTYPE html>
<html lang="en-US">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Today's Date</title>
    <script>
        let d = new Date();
        alert("Today's date is " + d);
    </script>
</head>
<body>
</body>
</html>