Angular TreeView - Accessibility

Accessibility Features Overview

NOTE
The overall accessibility level of your application depends on the TreeView features that you use.
Accessibility Requirement Support Level
Right-to-Left Support
Keyboard Navigation Support
Screen Reader Support
Contrast Color Theme
Mobile Device Support
Lighthouse Accessibility Validation
Axe Accessibility Validation
WAVE Accessibility Validation
Section 508 Support
WCAG 2.x Support
  • - All component features meet the requirement
  • - Some component features may not meet the requirement
  • - Accessibility requirement is not supported

Accessibility Standards Compliance

The TreeView component meets a variety of Section 508 and WCAG 2.x compliance standards. Known exceptions:

Section 508 criteria WCAG 2.x criteria Exception description
501 (Web)(Software)
504.2 (Authoring Tool)
602.3 (Support Docs)		 1.4.3 Contrast (Minimum) (Level AA)
1.4.11 Non-text Contrast (Level AA 2.1 and 2.2)		 TreeView does not support Windows High Contrast themes.

Keyboard Navigation

A user can use the following keys to interact with the TreeView component:

Key Action
Shift + Mouse Wheel Scrolls the content left/right if the scrollDirection property is "horizontal" or "both".
↑ / ↓ Moves focus to the previous/next node.
Home / End Moves focus to the first/last node.
→ Expands the node.
← Collapses the node.
Asterisk Sign (*) Expands all nodes. Available only if expandAllEnabled is set to true.
Minus Sign (-) Collapses all nodes. Available only if expandAllEnabled is set to true.
Enter or Space Selects the node.
Shift + ↑ / Shift + ↓ Extends selection up/down by one node.1
Shift + Home Extends selection up to the first node.1
Shift + End Extends selection down to the last node.1
  1. If showCheckBoxesMode is set to "none", this action has no effect.

Use the registerKeyHandler(key, handler) method to implement a custom handler for a key.

jQuery
JavaScript
function registerKeyHandlers () {
    const treeView = $("#treeViewContainer").dxTreeView("instance");
    treeView.registerKeyHandler("backspace", function(e) {
        // The argument "e" contains information on the event
    });
    treeView.registerKeyHandler("space", function(e) {
        // ...
    });
}
Angular
TypeScript
import { ..., ViewChild, AfterViewInit } from '@angular/core';
import { DxTreeViewModule, DxTreeViewComponent } from 'devextreme-angular';
// ...
export class AppComponent implements AfterViewInit {
    @ViewChild(DxTreeViewComponent, { static: false }) treeView: DxTreeViewComponent;
    // Prior to Angular 8
    // @ViewChild(DxTreeViewComponent) treeView: DxTreeViewComponent;

    ngAfterViewInit () {
        this.treeView.instance.registerKeyHandler('backspace', function(e) {
            // The argument "e" contains information on the event
        });
        this.treeView.instance.registerKeyHandler('space', function(e) {
            // ...
        });
    }
}
@NgModule({
    imports: [
        // ...
        DxTreeViewModule
    ],
    // ...
})
Vue
<template>
    <DxTreeView :ref="myTreeViewRef" />
</template>
<script>
import 'devextreme/dist/css/dx.light.css';

import DxTreeView from 'devextreme-vue/tree-view';

const myTreeViewRef = 'my-tree-view';

export default {
    components: {
        DxTreeView
    },
    data() {
        return {
            myTreeViewRef
        }
    },
    computed: {
        treeView: function() {
            return this.$refs[myTreeViewRef].instance;
        }
    },
    mounted: function() {
        this.treeView.registerKeyHandler('backspace', function(e) {
            // The argument "e" contains information on the event
        });
        this.treeView.registerKeyHandler('space', function(e) {
            // ...
        });
    }
}
</script>
React
App.js
import React from 'react';
import 'devextreme/dist/css/dx.light.css';

import { TreeView } from 'devextreme-react/tree-view';

class App extends React.Component {
    constructor(props) {
        super(props);

        this.treeViewRef = React.createRef();
    }

    render() {
        return (
            <TreeView ref={this.treeViewRef} />
        );
    }

    get treeView() {
        return this.treeViewRef.current.instance();
    }

    componentDidMount() {
        this.treeView.registerKeyHandler('backspace', function(e) {
            // The argument "e" contains information on the event
        });
        this.treeView.registerKeyHandler('space', function(e) {
            // ...
        });
    }
}

export default App;

Screen Reader Support

The TreeView component supports screen readers and complies to WAI-ARIA standards.