Angular TreeView Methods

The key.

collapseItem(itemElement)

Collapses an item found using its DOM node.

Parameters:

itemElement:

The item's DOM node.

collapseItem(key)

Collapses an item with a specific key.

Parameters:

key: any

The item's key.

defaultOptions(rule)

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

Parameters:

rule:

The component's default device options.

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 options should be applied to the device.
options	Object	Options to be applied.

Name

Type

Description

device

Device

|

Array<Device>

|

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

options

Options to be applied.

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

jQuery

JavaScript

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

Angular

TypeScript

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

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 options
    }
});

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 options
            }
        })
        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 widget:

jQuery

JavaScript

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

Angular

HTML

<dx-tree-view #treeViewVar id="myTreeView"></dx-tree-view>

TypeScript

import { ..., ViewChild } from "@angular/core";
import { DxTreeViewComponent } from "devextreme-angular";
// ...
export class AppComponent {
    @ViewChild("treeViewVar", { static: false }) treeView: DxTreeViewComponent;
    // Prior to Angular 8
    // @ViewChild("treeViewVar") treeView: DxTreeViewComponent;

    removeTreeView (e) {
        this.treeView.instance.dispose();
        document.getElementById("myTreeView").remove();
    }
}

element()

Gets the root widget element.

Return Value:

HTMLElement | jQuery

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

endUpdate()

Refreshes the widget after a call of the beginUpdate() method.

Main article: beginUpdate()

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.

expandItem(itemElement)

Expands an item found using its DOM node.

Parameters:

itemElement:

The item's DOM node.

expandItem(key)

Expands an item with a specific key.

Parameters:

key: any

The item's key.

focus()

Sets focus on the widget.

getDataSource()

Gets the DataSource instance.

Return Value:

DataSource

The DataSource instance.

NOTE

This method returns the DataSource instance even if the widget's dataSource option was given a simple array.

getInstance(element)

Gets the instance of a widget found using its DOM node.

Parameters:

element:

|

jQuery

The widget's container.

Return Value:

The widget's instance.

getInstance is a static method that the widget 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.

instance()

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

Return Value:

This widget's instance.

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.

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.

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.

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.

option()

Gets all widget options.

Return Value:

The widget's options.

option(optionName)

Gets the value of a single option.

Parameters:

optionName:

The option's name or full path.

Return Value: any

This option's value.

option(optionName, optionValue)

Updates the value of a single option.

Parameters:

optionName:

The option's name or full path.

optionValue: any

This option's new value.

option(options)

Updates the values of several options.

Parameters:

options:

Options with their new values.

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 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.

repaint()

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

selectAll()

Selects all items.

selectItem(itemData)

Selects an item found using its data object.

Parameters:

itemData:

The item's data object.

selectItem(itemElement)

Selects an item found using its DOM node.

Parameters:

itemElement:

The item's DOM node.

selectItem(key)

Selects an item with a specific key.

Parameters:

key: any

The item's key.

unselectAll()

Cancels the selection of all items.

unselectItem(itemData)

Cancels the selection of an item found using its data object.

Parameters:

itemData:

The item's data object.

unselectItem(itemElement)

Cancels the selection of an item found using its DOM node.

Parameters:

itemElement: