Methods

This section describes members used to manipulate the UI component.

See Also

beginUpdate()

Prevents the UI component from refreshing until the endUpdate() method is called.

The beginUpdate() and endUpdate() methods prevent the UI component from excessive updates when you are changing multiple UI component settings at once. After the beginUpdate() method is called, the UI component does not update its UI until the endUpdate() method is called.

See Also

collapseAll()

Collapses all items.

collapseItem(itemData)

Collapses an item with a specific key.

Parameters:
itemData:

Object

The 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.

collapseItem(itemElement)

Collapses an item found using its DOM node.

Parameters:
itemElement:

Element

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:

Object

The component's default device properties.

Object structure:
Name Type Description
device

Device

|

Array<Device>

|

Function

Device parameters.
When specifying 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.

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 from "devextreme/ui/tree_view";
// ...
export class AppComponent {
    constructor () {
        TreeView.defaultOptions({
            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 React from "react";
import dxTreeView from "devextreme/ui/tree_view";
import TreeView from "devextreme-react/tree-view";

class App extends React.Component {
    render () {
        dxTreeView.defaultOptions({
            device: { deviceType: "desktop" },
            options: {
                // Here go the TreeView properties
            }
        })
        return (
            <div>
                <TreeView id="treeView1" />
                <TreeView id="treeView2" />
            </div>
        )
    }
}

export default App;

dispose()

Disposes of all the resources allocated to the TreeView instance.

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

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

Use this method only if the UI component was created with jQuery or pure JavaScript. In Angular, Vue, and React, use conditional rendering:

Angular
app.component.html
<dx-tree-view ...
    *ngIf="condition">
</dx-tree-view>
Vue
App.vue
<template>
    <DxTreeView ...
        v-if="condition">
    </DxTreeView>
</template>

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

export default {
    components: {
        DxTreeView
    }
}
</script>
React
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;
See Also

element()

Gets the root UI component element.

Return Value:

HTMLElement or jQuery

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

See Also

endUpdate()

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

Main article: beginUpdate()

See Also

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:

Object

The item's data object.

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:

Element

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.

See Also

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.
See Also

getInstance(element)

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

Parameters:
element:

Element

|

jQuery

The UI component's container.

Return Value:

Object

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);
See Also

getNodes()

Gets all nodes.

Return Value:

Array<TreeView Node>

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

getSelectedNodeKeys()

Gets the keys of selected nodes.

Return Value:

Array<any>

The keys of selected nodes.

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.common.css';
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.common.css';
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;
See Also

instance()

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

Return Value:

TreeView

This UI component's instance.

See Also

off(eventName)

Detaches all event handlers from a single event.

Parameters:
eventName:

String

The event's name.

Return Value:

TreeView

The object for which this method is called.

See Also

off(eventName, eventHandler)

Detaches a particular event handler from a single event.

Parameters:
eventName:

String

The event's name.

eventHandler:

Function

The event's handler.

Return Value:

TreeView

The object for which this method is called.

See Also

on(eventName, eventHandler)

Subscribes to an event.

Parameters:
eventName:

String

The event's name.

eventHandler:

Function

The event's handler.

Return Value:

TreeView

The object for which this method is called.

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

See Also

on(events)

Subscribes to events.

Parameters:
events:

Object

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

Return Value:

TreeView

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.

See Also

option()

Return Value:

Object

The UI component's properties.

option(optionName)

Gets the value of a single property.

Parameters:
optionName:

String

The property's name or full path.

Return Value: any

This property's value.

option(optionName, optionValue)

Updates the value of a single property.

Parameters:
optionName:

String

The property's name or full path.

optionValue: any

This property's new value.

option(options)

Updates the values of several properties.

Parameters:
options:

Object

Options with their new values.

registerKeyHandler(key, handler)

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

Parameters:
key:

String

A key.

handler:

Function

A handler. Accepts the keydown event as the argument. It is a dxEvent 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.

See Also

repaint()

Repaints the UI component without reloading data. Call it to update the UI component's markup.

See Also

resetOption(optionName)

Resets an property to its default value.

Parameters:
optionName:

String

An property's name.

See Also

scrollToItem(itemData)

Scrolls the content to an item found using its data.

Parameters:
itemData:

Object

The item's data object.

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:

Element

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.

See Also

selectItem(itemData)

Selects a node found using its data object.

Parameters:
itemData:

Object

A data object.

Return Value:

Boolean

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.

See Also

selectItem(itemElement)

Selects a TreeView node found using its DOM node.

Parameters:
itemElement:

Element

A DOM node.

Return Value:

Boolean

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.

See Also

selectItem(key)

Selects a node with a specific key.

Parameters:
key: any

A key.

Return Value:

Boolean

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.

See Also

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.

See Also

unselectItem(itemData)

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

Parameters:
itemData:

Object

A data object.

Return Value:

Boolean

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.

See Also

unselectItem(itemElement)

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

Parameters:
itemElement:

Element

A DOM node.

Return Value:

Boolean

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.

See Also

unselectItem(key)

Cancels the selection of a node with a specific key.

Parameters:
key: any

A key.

Return Value:

Boolean

false if no node matches the specified key.

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.

See Also

updateDimensions()

Updates the tree view scrollbars according to the current size of the UI component content.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved if the UI component is updated and rejected otherwise. It is a native Promise or a jQuery.Promise when you use jQuery.