Accordion tree in EJ2 TypeScript Treeview control

Accordion is an interface where a list of items can be collapsed or expanded, but only one list can be collapsed or expanded at a time. You can customize the TreeView to make it behave as an accordion. Refer to the following code sample to create an accordion tree.

import { TreeView } from '@syncfusion/ej2-navigations';

/**
 * Accordion tree sample
 */
    // Hierarchical data source for TreeView component
   let continents: { [key: string]: Object; }[] = [
    {
        code: "AF", name: "Africa", countries: [
            { code: "NGA", name: "Nigeria" },
            { code: "EGY", name: "Egypt" },
            { code: "ZAF", name: "South Africa" }
        ]
    },
    {
        code: "AS", name: "Asia", countries: [
            { code: "CHN", name: "China" },
            { code: "IND", name: "India", selected: true },
            { code: "JPN", name: "Japan" }
        ]
    },
    {
        code: "EU", name: "Europe", countries: [
            { code: "DNK", name: "Denmark" },
            { code: "FIN", name: "Finland" },
            { code: "AUT", name: "Austria",
             }
        ]
    },
    {
        code: "NA", name: "North America", countries: [
            { code: "USA", name: "United States of America" },
            { code: "CUB", name: "Cuba" },
            { code: "MEX", name: "Mexico" }
        ]
    },
    {
        code: "OC", name: "Oceania", countries: [
            { code: "AUS", name: "Australia" },
            { code: "NZL", name: "New Zealand" },
            { code: "WSM", name: "Samoa" }
        ]
    },
];

// Render treeview with cssClass
let tree1: TreeView = new TreeView({
    fields: { dataSource: continents, id: "code", text: "name", child: "countries" },
    nodeSelected: nodeSelect,
    cssClass: ("accordiontree")
});
tree1.appendTo('#tree');

function nodeSelect (args: NodeSelectEventArgs) {
    if (args.node.classList.contains('e-level-1')) {
        this.collapseAll();
        this.expandAll([args.node]);
    }
}
<!DOCTYPE html>
<html lang="en">

<head>
    <title>Essential JS 2 for TreeView </title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 for TreeView UI Control" />
    <meta name="author" content="Syncfusion" />
    <link href="index.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.1.35/ej2-navigations/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>Loading....</div>
    <div id='container'>
        <div id='treeparent'>
            <div id="tree"></div>
        </div>
    </div>
</body>

</html>
#container {
    visibility: hidden;
}

#loader {
  color: #008cff;
  height: 40px;
  width: 30%;
  position: absolute;
  font-family: 'Helvetica Neue','calibiri';
  font-size: 14px;
  top: 45%;
  left: 45%;
}

#treeparent {
    display: block;
    max-width: 350px;
    max-height: 350px;
    margin: auto;
    overflow: auto;
    padding-top: 50px;
}
.accordiontree .e-list-item.e-level-1 > .e-fullrow, .accordiontree .e-list-item.e-level-1.e-active > .e-fullrow,  .accordiontree .e-list-item.e-level-1.e-hover > .e-fullrow , .accordiontree .e-list-item.e-level-1 > .e-fullrow, .accordiontree .e-list-item.e-level-1.e-active.e-hover > .e-fullrow {
    background-color: darkslateblue;
    border-color: darkslateblue;
}

.accordiontree .e-list-item.e-level-1 > .e-text-content .e-list-text, .accordiontree .e-list-item.e-level-1.e-active > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-1.e-hover > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-1.e-active.e-hover > .e-text-content .e-list-text {
    color: white;
    font-size: 16px;
} 
.accordiontree .e-list-item.e-level- .e-icons.e-icon-collapsible, .accordiontree .e-list-item.e-level-1 .e-icons.e-icon-collapsible,.accordiontree .e-list-item.e-level-1 .e-icon-expandable {
    display: none
}

.accordiontree .e-list-item.e-level-2 > .e-fullrow, .accordiontree .e-list-item.e-level-2.e-active > .e-fullrow,  .accordiontree .e-list-item.e-level-2.e-hover > .e-fullrow , .accordiontree .e-list-item.e-level-2 > .e-fullrow, .accordiontree .e-list-item.e-level-2.e-active.e-hover > .e-fullrow {
    background-color: white;
    border-color: white;
}

.accordiontree .e-list-item.e-level-2 > .e-text-content .e-list-text, .accordiontree .e-list-item.e-level-2.e-active > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-2.e-hover > .e-text-content .e-list-text,  .accordiontree .e-list-item.e-level-2.e-active.e-hover > .e-text-content .e-list-text {
    color: blue;
    font-size: 14px;
}