<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Bootstrap 4 DatePicker</title>
    <script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
    <script src="https://unpkg.com/gijgo@1.9.11/js/gijgo.min.js" type="text/javascript"></script>
    <link href="https://unpkg.com/gijgo@1.9.11/css/gijgo.min.css" rel="stylesheet" type="text/css" />
</head>
<body>
    <input type="text" id="datepicker" width="276" />
    <script>
        $('#datepicker').datepicker({
            uiLibrary: 'bootstrap4'
        });
    </script>
</body>
</html>