Virtual scroll in EJ2 TypeScript Treegrid control

3 Jan 202413 minutes to read

TreeGrid allows you to load large amount of data without performance degradation.

To use virtualization, you need to inject VirtualScroll module in treegrid.

Row virtualization

Row virtualization allows you to load and render rows only in the content viewport. It is an alternative way of paging in which the rows will be appended while scrolling vertically. To setup the row virtualization, you need to define
enableVirtualization as true and content height by height property.

The number of records displayed in the TreeGrid is determined implicitly by height of the content area and a buffer records will be maintained in the TreeGrid content in addition to the original set of rows.

Expand and Collapse state of any child record will be persisted.

import { VirtualScroll, TreeGrid } from '@syncfusion/ej2-treegrid';
import { virtualData, dataSource } from './datasource.ts';

TreeGrid.Inject(VirtualScroll);

dataSource();

let treegrid: TreeGrid = new TreeGrid(
        {
            dataSource: virtualData,
            enableVirtualization: true,
            treeColumnIndex: 1,
            childMapping: 'Crew',
            height: 317,
            columns: [
                { field: 'TaskID', headerText: 'Player Jersey', width: 140, textAlign: 'Right' },
                { field: 'FIELD1', headerText: 'Player Name', width: 140 },
                { field: 'FIELD2', headerText: 'Year', width: 120, textAlign: 'Right' },
                { field: 'FIELD3', headerText: 'Stint', width: 120, textAlign: 'Right' },
                { field: 'FIELD4', headerText: 'TMID', width: 120, textAlign: 'Right' }
               ]
        });
    treegrid.appendTo('#TreeGrid');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 TreeGrid</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Typescript TreeGrid Control" />
    <meta name="author" content="Syncfusion" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-grids/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-buttons/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-popups/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-navigations/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-dropdowns/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-lists/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-calendars/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-treegrid/styles/material.css" rel="stylesheet" />
    
    
    
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-splitbuttons/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='TreeGrid'></div>
    </div>
</body>
</html>

Column virtualization

Column virtualization allows you to virtualize columns. It will render column only in the current view port and all other columns are rendered on demand during horizontal scrolling.

To setup the column virtualization, set the
enableVirtualization and
enableColumnVirtualization properties as true.

import { VirtualScroll, TreeGrid } from '@syncfusion/ej2-treegrid';
import { virtualData, dataSource } from './datasource.ts';

TreeGrid.Inject(VirtualScroll);

dataSource();

let treegrid: TreeGrid = new TreeGrid({
  dataSource: virtualData,
  enableVirtualization: true,
  enableColumnVirtualization: true,
  treeColumnIndex: 1,
  childMapping: 'Crew',
  height: 317,
  columns: [
    {
      field: 'TaskID',
      headerText: 'Player Jersey',
      width: 140,
      textAlign: 'Right'
    },
    { field: 'FIELD1', headerText: 'Player Name', width: 140 },
    { field: 'FIELD2', headerText: 'Year', width: 120, textAlign: 'Right' },
    { field: 'FIELD3', headerText: 'Stint', width: 120, textAlign: 'Right' },
    { field: 'FIELD4', headerText: 'TMID', width: 120, textAlign: 'Right' },
    { field: 'FIELD5', headerText: 'LGID', width: 120, textAlign: 'Right' },
    { field: 'FIELD6', headerText: 'GP', width: 120, textAlign: 'Right' },
    { field: 'FIELD7', headerText: 'GS', width: 120, textAlign: 'Right' },
    { field: 'FIELD8', headerText: 'Minutes', width: 120, textAlign: 'Right' },
    { field: 'FIELD9', headerText: 'Points', width: 120, textAlign: 'Right' },
    { field: 'FIELD10', headerText: 'oRebounds', width: 120, textAlign: 'Right' },
    { field: 'FIELD11', headerText: 'dRebounds', width: 120, textAlign: 'Right' },
    { field: 'FIELD12', headerText: 'Rebounds', width: 120, textAlign: 'Right' },
    { field: 'FIELD13', headerText: 'Assists', width: 120, textAlign: 'Right' },
    { field: 'FIELD14', headerText: 'Steals', width: 120, textAlign: 'Right' },
    { field: 'FIELD15', headerText: 'Blocks', width: 120, textAlign: 'Right' },
    { field: 'FIELD16', headerText: 'Turnovers', width: 120, textAlign: 'Right' },
    { field: 'FIELD17', headerText: 'PF', width: 120, textAlign: 'Right' },
    { field: 'FIELD18', headerText: 'fgAttempted', width: 120, textAlign: 'Right' },
    { field: 'FIELD19', headerText: 'ftAttempted', width: 120, textAlign: 'Right' },
    { field: 'FIELD20', headerText: 'ThreeAttempted', width: 120, textAlign: 'Right' },
    { field: 'FIELD21', headerText: 'ThreeMade', width: 120, textAlign: 'Right' },
    { field: 'FIELD22', headerText: 'PostGP', width: 120, textAlign: 'Right' },
    { field: 'FIELD23', headerText: 'ftMade', width: 120, textAlign: 'Right' },
    { field: 'FIELD24', headerText: 'fgMade', width: 120, textAlign: 'Right' },
    { field: 'FIELD25', headerText: 'ffmade', width: 120, textAlign: 'Right' },
    { field: 'FIELD26', headerText: 'PostGS', width: 120, textAlign: 'Right' },
    { field: 'FIELD27', headerText: 'PostMinutes', width: 120, textAlign: 'Right' },
    { field: 'FIELD28', headerText: 'PostPoints', width: 120, textAlign: 'Right' },
    { field: 'FIELD29', headerText: 'PostoRebounds', width: 120, textAlign: 'Right' },
    { field: 'FIELD30', headerText: 'PostdRebounds', width: 120, textAlign: 'Right' }
  ]
});
treegrid.appendTo('#TreeGrid');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 TreeGrid</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Typescript TreeGrid Control" />
    <meta name="author" content="Syncfusion" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-grids/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-buttons/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-popups/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-navigations/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-dropdowns/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-lists/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-inputs/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-calendars/styles/material.css" rel="stylesheet" />
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-treegrid/styles/material.css" rel="stylesheet" />
    
    
    
    <link href="https://cdn.syncfusion.com/ej2/25.2.3/ej2-splitbuttons/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='TreeGrid'></div>
    </div>
</body>
</html>

Column’s width is required for column virtualization. If column’s width is not defined then tree grid will consider its value as 200px.

Limitations for virtualization

  • Due to the element height limitation in browsers, the maximum number of records loaded by the treegrid is limited by the browser capability.
  • Cell selection will not be persisted in row.
  • The page size provided must be two times larger than the number of visible rows in the grid. If the page size is failed to meet this condition then the size will be determined by TreeGrid.
  • The virtual height of the treegrid content is calculated using the row height and total number of records in the data source and hence features which changes row height such as text wrapping are not supported. If you want to increase the row height to accommodate the content then you can specify the row height as below to ensure all the table rows are in same height.
.e-treegrid .e-row {
    height: 2em;
}
  • Programmatic selection using the selectRows method is not supported in virtual scrolling.
  • Virtual scrolling is not compatible with Batch editing, clipboard functionality and detail template.
  • When virtualization is active in a tree grid, the editCell method is unusable for records outside the currently visible viewport.

You can refer to our JavaScript Tree Grid feature tour page for its groundbreaking feature representations. You can also explore our JavaScript Tree Grid example JavaScript Tree Grid example to knows how to present and manipulate data.