Angular TreeView Methods

The item's DOM node.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the item is collapsed and rejected if the item is nonexistent or disabled.
It is a native Promise or a jQuery.Promise when you use jQuery.

collapseItem(key)

Collapses an item with a specific key.

Parameters:

key: any

The item's key.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the item is collapsed and rejected if the item is nonexistent or disabled.
It is a native Promise or a jQuery.Promise when you use jQuery.

defaultOptions(rule)

Specifies the device-dependent default configuration properties for this component.

Parameters:

rule:

The component's default device properties.

Object structure:

Name	Type	Description
device	Device \| Function	Device parameters. When you specify a function, get information about the current device from the argument. Return true if the properties should be applied to the device.
options	Object	Options to be applied.

Name

Type

Description

device

Device

|

Device parameters.
When you specify a function, get information about the current device from the argument. Return true if the properties should be applied to the device.

options

Options to be applied.

defaultOptions is a static method that the UI component class supports. The following code demonstrates how to specify default properties for all instances of the TreeView UI component in an application executed on the desktop.

jQuery

JavaScript

DevExpress.ui.dxTreeView.defaultOptions({ 
    device: { deviceType: "desktop" },
    options: {
        // Here go the TreeView properties
    }
});

Angular

TypeScript

import TreeView, { Properties } from "devextreme/ui/tree_view";
// ...
export class AppComponent {
    constructor () {
        TreeView.defaultOptions<Properties>({
            device: { deviceType: "desktop" },
            options: {
                // Here go the TreeView properties
            }
        });
    }
}

Vue

<template>
    <div>
        <DxTreeView id="treeView1" />
        <DxTreeView id="treeView2" />
    </div>
</template>
<script>
import DxTreeView from "devextreme-vue/tree-view";
import TreeView from "devextreme/ui/tree_view";

TreeView.defaultOptions({
    device: { deviceType: "desktop" },
    options: {
        // Here go the TreeView properties
    }
});

export default {
    components: {
        DxTreeView
    }
}
</script>

React

import dxTreeView from "devextreme/ui/tree_view";
import TreeView from "devextreme-react/tree-view";

dxTreeView.defaultOptions({
    device: { deviceType: "desktop" },
    options: {
        // Here go the TreeView properties
    }
});

export default function App() {
    return (
        <div>
            <TreeView id="treeView1" />
            <TreeView id="treeView2" />
        </div>
    )
}

You can also set rules for multiple device types:

jQuery

JavaScript

const devicesConfig = [
    { deviceType: 'desktop' },
    { deviceType: 'tablet' },
    { deviceType: 'phone' },
];

devicesConfig.forEach(deviceConfig => {
    DevExpress.ui.dxTreeView.defaultOptions({ 
        device: deviceConfig,
        options: {
            // Here go the TreeView properties
        }
    });
});

Angular

TypeScript

import TreeView, { Properties } from "devextreme/ui/tree_view";
// ...
export class AppComponent {
    constructor () {
        const devicesConfig = [
            { deviceType: 'desktop' },
            { deviceType: 'tablet' },
            { deviceType: 'phone' },
        ];

        devicesConfig.forEach(deviceConfig => {
            TreeView.defaultOptions<Properties>({
                device: deviceConfig,
                options: {
                    // Here go the TreeView properties
                }
            });
        });
    }
}

Vue

<template>
    <div>
        <DxTreeView />
    </div>
</template>
<script>
import DxTreeView from "devextreme-vue/tree-view";
import TreeView from "devextreme/ui/tree_view";

const devicesConfig = [
    { deviceType: 'desktop' },
    { deviceType: 'tablet' },
    { deviceType: 'phone' },
];

devicesConfig.forEach(deviceConfig => {
    TreeView.defaultOptions({
        device: deviceConfig,
        options: {
            // Here go the TreeView properties
        }
    });
});

export default {
    components: {
        DxTreeView
    }
}
</script>

React

import dxTreeView from "devextreme/ui/tree_view";
import TreeView from "devextreme-react/tree-view";

const devicesConfig = [
    { deviceType: 'desktop' },
    { deviceType: 'tablet' },
    { deviceType: 'phone' },
];

devicesConfig.forEach(deviceConfig => {
    dxTreeView.defaultOptions({
        device: deviceConfig,
        options: {
            // Here go the TreeView properties
        }
    });
});

export default function App() {
    return (
        <div>
            <TreeView />
        </div>
    )
}

dispose()

Disposes of all the resources allocated to the TreeView instance.

jQuery

After calling this method, remove the DOM element associated with the UI component:

JavaScript

$("#myTreeView").dxTreeView("dispose");
$("#myTreeView").remove();

Angular

Use conditional rendering instead of this method:

app.component.html

<dx-tree-view ...
    *ngIf="condition">
</dx-tree-view>

Vue

Use conditional rendering instead of this method:

App.vue

<template>
    <DxTreeView ...
        v-if="condition">
    </DxTreeView>
</template>

<script>
import DxTreeView from 'devextreme-vue/tree-view';

export default {
    components: {
        DxTreeView
    }
}
</script>

React

Use conditional rendering instead of this method:

App.js

import React from 'react';

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

function DxTreeView(props) {
    if (!props.shouldRender) {
        return null;
    }

    return (
        <TreeView ... >    
        </TreeView>
    );
}

class App extends React.Component {
    render() {
        return (
            <DxTreeView shouldRender="condition" />
        );
    }
}
export default App;

element()

Gets the root UI component element.

Return Value:

HTMLElement | jQuery

An HTML element or a jQuery element when you use jQuery.

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endUpdate()

Refreshes the UI component after a call of the beginUpdate() method.

The beginUpdate() and endUpdate() methods reduce the number of renders in cases where extra rendering can negatively affect performance.

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expandAll()

Expands all items. If you load items on demand, this method expands only the loaded items.

expandItem(itemData)

Expands an item found using its data object.

Parameters:

itemData:

|

The item's data object.

Object structure:

Name	Type	Description
disabled	Boolean	Specifies whether the UI component item responds to user interaction.
expanded	Boolean	Specifies whether or not the tree view item is displayed expanded.
hasItems	Boolean	Specifies whether or not the tree view item has children.
html	String	Specifies the HTML markup to be inserted into the item element.
icon	String	Specifies the tree view item's icon.
id	Number \| String	Holds the unique key of an item.
items	Array<dxTreeViewItem>	Specifies nested tree view items.
parentId	Number \| String	Holds the key of the parent item.
selected	Boolean	Specifies whether the TreeView item should be displayed as selected.
template	template \| Function	Specifies a template that should be used to render this item only.
text	String	Specifies text displayed for the UI component item.
visible	Boolean	Specifies whether or not a UI component item must be displayed.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the item is expanded and rejected if the item is nonexistent or disabled.
It is a native Promise or a jQuery.Promise when you use jQuery.

expandItem(itemElement)

Expands an item found using its DOM node.

Parameters:

itemElement:

The item's DOM node.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the item is expanded and rejected if the item is nonexistent or disabled.
It is a native Promise or a jQuery.Promise when you use jQuery.

expandItem(key)

Expands an item with a specific key.

Parameters:

key: any

The item's key.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the item is expanded and rejected if the item is nonexistent or disabled.
It is a native Promise or a jQuery.Promise when you use jQuery.

focus()

Sets focus on the UI component.

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getDataSource()

Gets the DataSource instance.

Return Value:

DataSource

The DataSource instance.

NOTE

This method returns the DataSource instance even if the UI component's dataSource property was given a simple array.

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getInstance(element)

Gets the instance of a UI component found using its DOM node.

Parameters:

element:

|

jQuery

The UI component's container.

Return Value:

The UI component's instance.

getInstance is a static method that the UI component class supports. The following code demonstrates how to get the TreeView instance found in an element with the myTreeView ID:

// Modular approach
import TreeView from "devextreme/ui/tree_view";
...
let element = document.getElementById("myTreeView");
let instance = TreeView.getInstance(element) as TreeView;

// Non-modular approach
let element = document.getElementById("myTreeView");
let instance = DevExpress.ui.dxTreeView.getInstance(element);

getNodes()

Gets all nodes.

Return Value:

Array<TreeView Node>

All nodes. Their structure is described in the Node section.

getScrollable()

Gets the instance of the UI component's scrollable part.

Return Value:

Scrollable

The scrollable part's instance.

For information on API members of the scrollable part, refer to the ScrollView section. The list below shows ScrollView members that are unavailable for this method.

Properties:

pullingDownText
pulledDownText
refreshingText
reachBottomText
onPullDown
onReachBottom

Methods:

release(preventScrollBottom)
refresh()

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getSelectedNodeKeys()

Gets the keys of selected nodes.

Return Value:

Array<any>

The keys of selected nodes.

View Demo

NOTE

If searching is applied, this method returns the keys of only those selected nodes that satisfy the search condition.

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getSelectedNodes()

Gets selected nodes.

Return Value:

Array<TreeView Node>

Selected nodes.

jQuery

index.js

const selectedNodes = $("#treeViewContainer").dxTreeView("getSelectedNodes");

Angular

app.component.ts

app.component.html

app.module.ts

import { Component, ViewChild } from '@angular/core';
import { DxTreeViewComponent } from 'devextreme-angular';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})
export class AppComponent {
    @ViewChild('treeViewRef', { static: false }) treeView: DxTreeViewComponent;
    // Prior to Angular 8
    // @ViewChild('treeViewRef') treeView: DxTreeViewComponent;

    selectedNodes = [];

    getSelectedNodes() {
        this.selectedNodes = this.treeView.instance.getSelectedNodes();
    }
}

<dx-tree-view ...
    #treeViewRef>
</dx-tree-view>

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';

import { DxTreeViewModule } from 'devextreme-angular';

@NgModule({
    declarations: [
        AppComponent
    ],
    imports: [
        BrowserModule,
        DxTreeViewModule
    ],
    providers: [ ],
    bootstrap: [AppComponent]
})
export class AppModule { }

Vue

App.vue

<template>
    <DxTreeView ...
        :ref="treeViewRef">
    </DxTreeView>
</template>

<script>
import 'devextreme/dist/css/dx.light.css';

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

export default {
    components: {
        DxTreeView
    },
    data() {
        return {
            treeViewRef,
            selectedNodes: []
        }
    },
    computed: {
        treeView: function() {
            return this.$refs[treeViewRef].instance;
        }
    },
    methods: {
        getSelectedNodes() {
            this.selectedNodes = this.treeView.getSelectedNodes();
        }
    }
}
</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();
        this.selectedNodes = [];
        this.getSelectedNodes = () => {
            this.selectedNodes = this.treeView.getSelectedNodes();
        }
    }

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

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

NOTE

If searching is applied, this method returns only those selected nodes that satisfy the search condition.

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instance()

Gets the UI component's instance. Use it to access other methods of the UI component.

Return Value:

This UI component's instance.

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off(eventName)

Detaches all event handlers from a single event.

Parameters:

eventName:

The event's name.

Return Value:

The object for which this method is called.

jQuery

Handle Events

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Event Handling

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Event Handling

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Event Handling

off(eventName, eventHandler)

Detaches a particular event handler from a single event.

Parameters:

eventName:

The event's name.

eventHandler:

The event's handler.

Return Value:

The object for which this method is called.

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Event Handling

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Event Handling

on(eventName, eventHandler)

Subscribes to an event.

Parameters:

eventName:

The event's name.

eventHandler:

The event's handler.

Return Value:

The object for which this method is called.

Use this method to subscribe to one of the events listed in the Events section.

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on(events)

Subscribes to events.

Parameters:

events:

Events with their handlers: { "eventName1": handler1, "eventName2": handler2, ...}

Return Value:

The object for which this method is called.

Use this method to subscribe to several events with one method call. Available events are listed in the Events section.

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option()

Gets all UI component properties.

Return Value:

The UI component's properties.

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option(optionName)

Gets the value of a single property.

Parameters:

optionName:

The property's name or full path.

Return Value: any

This property's value.

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option(optionName, optionValue)

Updates the value of a single property.

Parameters:

optionName:

The property's name or full path.

optionValue: any

This property's new value.

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option(options)

Updates the values of several properties.

Parameters:

options:

Options with their new values.

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registerKeyHandler(key, handler)

Registers a handler to be executed when a user presses a specific key.

Parameters:

key:

A key.

handler:

A handler. Accepts the keydown event as the argument. It is a EventObject or a jQuery.Event when you use jQuery.

The key argument accepts one of the following values:

"backspace"
"tab"
"enter"
"escape"
"pageUp"
"pageDown"
"end"
"home"
"leftArrow"
"upArrow"
"rightArrow"
"downArrow"
"del"
"space"
"F"
"A"
"asterisk"
"minus"

A custom handler for a key cancels the default handler for this key.

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repaint()

Renders the component again without reloading data. Use the method to update the component's markup and appearance dynamically.

The repaint() method re-initializes the component with new settings, resetting its state and history.

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resetOption(optionName)

Resets a property to its default value.

Parameters:

optionName:

A property's name.

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scrollToItem(itemData)

Scrolls the content to an item found using its data.

Parameters:

itemData:

|

The item's data object.

Object structure:

Name	Type	Description
disabled	Boolean	Specifies whether the UI component item responds to user interaction.
expanded	Boolean	Specifies whether or not the tree view item is displayed expanded.
hasItems	Boolean	Specifies whether or not the tree view item has children.
html	String	Specifies the HTML markup to be inserted into the item element.
icon	String	Specifies the tree view item's icon.
id	Number \| String	Holds the unique key of an item.
items	Array<dxTreeViewItem>	Specifies nested tree view items.
parentId	Number \| String	Holds the key of the parent item.
selected	Boolean	Specifies whether the TreeView item should be displayed as selected.
template	template \| Function	Specifies a template that should be used to render this item only.
text	String	Specifies text displayed for the UI component item.
visible	Boolean	Specifies whether or not a UI component item must be displayed.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the content is scrolled to the target item and rejected if the item is nonexsistent or nested in a collapsed and disabled node.
It is a native Promise or a jQuery.Promise when you use jQuery.

scrollToItem(itemElement)

Scrolls the content to an item found using its DOM node.

Parameters:

itemElement:

The item's DOM node.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the content is scrolled to the target item and rejected if the item is nonexsistent or nested in a collapsed and disabled node.
It is a native Promise or a jQuery.Promise when you use jQuery.

scrollToItem(key)

Scrolls the content to an item found using its key.

Parameters:

key: any

The item's key.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the content is scrolled to the target item and rejected if the item is nonexsistent or nested in a collapsed and disabled node.
It is a native Promise or a jQuery.Promise when you use jQuery.

selectAll()

Selects all nodes.

This method has the following specificities:

Only loaded nodes can be selected. Take this specificity into account if nodes are loaded on demand (for example, if you use the virtual mode or createChildren function).
If searching is applied, only the nodes that satisfy the search condition can be selected.

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selectItem(itemData)

Selects a node found using its data object.

Parameters:

itemData:

|

A data object.

Object structure:

Name	Type	Description
disabled	Boolean	Specifies whether the UI component item responds to user interaction.
expanded	Boolean	Specifies whether or not the tree view item is displayed expanded.
hasItems	Boolean	Specifies whether or not the tree view item has children.
html	String	Specifies the HTML markup to be inserted into the item element.
icon	String	Specifies the tree view item's icon.
id	Number \| String	Holds the unique key of an item.
items	Array<dxTreeViewItem>	Specifies nested tree view items.
parentId	Number \| String	Holds the key of the parent item.
selected	Boolean	Specifies whether the TreeView item should be displayed as selected.
template	template \| Function	Specifies a template that should be used to render this item only.
text	String	Specifies text displayed for the UI component item.
visible	Boolean	Specifies whether or not a UI component item must be displayed.

Return Value:

false if no node was found.

This method has the following specificities:

Only loaded nodes can be selected. Take this specificity into account if nodes are loaded on demand (for example, if you use the virtual mode or createChildren function).
If searching is applied, only the nodes that satisfy the search condition can be selected.

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selectItem(itemElement)

Selects a TreeView node found using its DOM node.

Parameters:

itemElement:

A DOM node.

Return Value:

false if no node was found.

This method has the following specificities:

Only loaded nodes can be selected. Take this specificity into account if nodes are loaded on demand (for example, if you use the virtual mode or createChildren function).
If searching is applied, only the nodes that satisfy the search condition can be selected.

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selectItem(key)

Selects a node with a specific key.

Parameters:

key: any

A key.

Return Value:

false if no node matches the specified key.

This method has the following specificities:

Only loaded nodes can be selected. Take this specificity into account if nodes are loaded on demand (for example, if you use the virtual mode or createChildren function).
If searching is applied, only the nodes that satisfy the search condition can be selected.

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unselectAll()

Cancels the selection of all nodes.

This method has the following specificities:

The selection of only loaded nodes can be canceled. Take this specificity into account if nodes are loaded on demand (for example, if you use the virtual mode or createChildren function).
If searching is applied, this method cancels the selection of only those nodes that satisfy the search condition.

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unselectItem(itemData)

Cancels the selection of a node found using its data object.

Parameters:

itemData:

|

A data object.

Object structure:

Name	Type	Description
disabled	Boolean	Specifies whether the UI component item responds to user interaction.
expanded	Boolean	Specifies whether or not the tree view item is displayed expanded.
hasItems	Boolean	Specifies whether or not the tree view item has children.
html	String	Specifies the HTML markup to be inserted into the item element.
icon	String	Specifies the tree view item's icon.
id	Number \| String	Holds the unique key of an item.
items	Array<dxTreeViewItem>	Specifies nested tree view items.
parentId	Number \| String	Holds the key of the parent item.
selected	Boolean	Specifies whether the TreeView item should be displayed as selected.
template	template \| Function	Specifies a template that should be used to render this item only.
text	String	Specifies text displayed for the UI component item.
visible	Boolean	Specifies whether or not a UI component item must be displayed.

Return Value:

false if no node was found.

This method has the following specificities:

The selection of only loaded nodes can be canceled. Take this specificity into account if nodes are loaded on demand (for example, if you use the virtual mode or createChildren function).
If searching is applied, this method cancels the selection of only those nodes that satisfy the search condition.

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unselectItem(itemElement)

Cancels the selection of a TreeView node found using its DOM node.

Parameters:

itemElement:

A DOM node.

Return Value:

false if no node was found.

This method has the following specificities:

The selection of only loaded nodes can be canceled. Take this specificity into account if nodes are loaded on demand (for example, if you use the virtual mode or createChildren function).
If searching is applied, this method cancels the selection of only those nodes that satisfy the search condition.

jQuery

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unselectItem(key)

Cancels the selection of a node with a specific key.

Parameters:

key: any

A key.

Return Value: