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. |
The component also complies with the European Accessibility Act (EAA) and Americans with Disabilities Act (ADA) directives.
Keyboard Navigation
TreeView offers different keyboard controls depending on the action users want to perform.
Navigation
| 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 (if expandAllEnabled is true). |
| Minus Sign (-) | Collapses all nodes (if expandAllEnabled is true). |
Selection
| Key | Action |
|---|---|
| Enter or Space | Selects the node. |
| Shift + ↑ / Shift + ↓ | Extends selection up/down by one node (if selectionMode is "multiple" or "all"). |
| Shift + Home | Extends selection up to the first node (if selectionMode is "multiple" or "all"). |
| Shift + End | Extends selection down to the last node (if selectionMode is "multiple" or "all"). |
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.
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