JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cdn.kendostatic.com/2013.2.716/js/kendo.all.min.js"></script>
<link rel="stylesheet" href="http://cdn.kendostatic.com/2013.2.716/styles/kendo.common.min.css">
<link rel="stylesheet" href="http://cdn.kendostatic.com/2013.2.716/styles/kendo.default.min.css">
<div class="demo-section">
    <strong>House</strong>
    <div id="treeview-left"></div>
</div>

JavaScript

var inlineDefault = new kendo.data.HierarchicalDataSource({
     data: [
         { text: "Furniture", hasChildren: true },
         { text: "Decor", hasChildren: true }
     ]
 });

$("#treeview-left").kendoTreeView({
    dataSource: inlineDefault,
    loadOnDemand: true,
    expand: OnNodeExpand,
});

function OnNodeExpand(e)
{
    //debugger;
    $(e.node).find('.k-icon').addClass('k-loading');
    var start = new Date().getTime();
    
    // Sleep for 5 seconds
    for (var i = 0; i < 1e7; i++) {
        if ((new Date().getTime() - start) > 5000){
            break;
        }
    } 
    
    $('#treeview-left').data('kendoTreeView').append({ text: 'Sparked', hasChildren: true}, $(e.node))
}