jQX Tree Example without weird children data

Tree grid example with jqwidget data

HTML

<script src="https://jqwidgets.com/public/jqwidgets/jqx-all.js"></script>
<link rel="stylesheet" href="https://jqwidgets.com/public/jqwidgets/styles/jqx.base.css">
<link rel="stylesheet" href="https://jqwidgets.com/public/jqwidgets/styles/jqx.energyblue.css">
<script src="https://jqwidgets.com/jquery-widgets-demo/demos/jqxgrid/generatedata.js"></script>
 <div id="treeGrid">
    </div>

CSS

.jqx-grid-cell input[type="button"]{
    width:100%;
    z-index:10;
    opacity:0.01!important;
    z-index:5!important;
    
    display:block!important;
}

JavaScript

var employees = [{
  "EmployeeID": 1,
  "FirstName": "Nancy",
  "LastName": "Davolio",
  "ReportsTo": 5,
  "Country": "USA",
  "Title": "Sales Representative",
  "HireDate": "1992-05-01 00:00:00",
  "BirthDate": "1948-12-08 00:00:00",
  "City": "Seattle",
  "Address": "507 - 20th Ave. E.Apt. 2A"
}, {
  "EmployeeID": 2,
  "FirstName": "Andrew",
  "LastName": "Fuller",
  "ReportsTo": 1,
  "Country": "USA",
  "Title": "Vice President, Sales",
  "HireDate": "1992-08-14 00:00:00",
  "BirthDate": "1952-02-19 00:00:00",
  "City": "Tacoma",
  "Address": "908 W. Capital Way"
}, {
  "EmployeeID": 3,
  "FirstName": "Janet",
  "LastName": "Leverling",
  "ReportsTo": 2,
  "Country": "USA",
  "Title": "Sales Representative",
  "HireDate": "1992-04-01 00:00:00",
  "BirthDate": "1963-08-30 00:00:00",
  "City": "Kirkland",
  "Address": "722 Moss Bay Blvd.",
  expanded: true
}, {
  "EmployeeID": 4,
  "FirstName": "Margaret",
  "LastName": "Peacock",
  "ReportsTo": 3,
  "Country": "USA",
  "Title": "Sales Representative",
  "HireDate": "1993-05-03 00:00:00",
  "BirthDate": "1937-09-19 00:00:00",
  "City": "Redmond",
  "Address": "4110 Old Redmond Rd."
}, {
  "EmployeeID": 5,
  "FirstName": "Steven",
  "LastName": "Buchanan",
  "ReportsTo": null,
  "Country": "UK",
  "Title": "Sales Manager",
  "HireDate": "1993-10-17 00:00:00",
  "BirthDate": "1955-03-04 00:00:00",
  "City": "London",
  "Address": "14 Garrett Hill",
  expanded: true
}];

// prepare the data
var source = {
  dataType: "json",
  dataFields: [{
      name: 'EmployeeID',
      type: 'number'
    },
    {
      name: 'ReportsTo',
      type: 'number'
    },
    {
      name: 'FirstName',
      type: 'string'
    },
    {
      name: 'LastName',
      type: 'string'
    },
    {
      name: 'Country',
      type: 'string'
    },
    {
      name: 'City',
      type: 'string'
    },
    {
      name: 'Address',
      type: 'string'
    },
    {
      name: 'Title',
      type: 'string'
    },
    {
      name:...