jQuery/src/index.html

<!DOCTYPE html>
<html>
<head>
    <title>DevExtreme TreeList with summary</title>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <link rel="icon" href="/favicon.ico">
    <link rel="stylesheet" type="text/css" href="../node_modules/devextreme/dist/css/dx.light.css" />
    <link rel="stylesheet" type="text/css" href="index.css" />
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
    <script type="text/javascript" src="https://cdn3.devexpress.com/jslib/21.1.3/js/dx.all.js"></script>
    <!-- <script type="text/javascript" src="../node_modules/jquery/dist/jquery.js"></script>
    <script type="text/javascript" src="../node_modules/devextreme/dist/js/dx.all.js"></script> -->
    <script type="text/javascript" src="index.js"></script>
    <script type="text/javascript" src="data.js"></script>
</head>
<body class="dx-viewport">
    <div class="demo-container">
        <div id="form">
            <div class="dx-fieldset">
                <div class="dx-field">
                    <div class="dx-field-label">DropDownBox with embedded TreeList</div>
                    <div class="dx-field-value">
                        <div id="treeBox"></div>
                    </div>
                </div>
            </div>
        </div>
    </div>
</body>
</html>