---
title: Virtualized Tree
lang: en-US
---

# <ElBadge value="beta">Tree V2 virtualized tree</ElBadge>

Tree view with blazing fast scrolling performance for any amount of data

## Basic usage

Basic tree structure.

:::demo

tree-v2/basic

:::

## Selectable

Used for node selection.

:::demo

tree-v2/selectable

:::

:::warning

When using show-checkbox, since `check-on-click-leaf` is true by default,
last tree children's can be checked by clicking their nodes.

:::

## Disabled checkbox

The checkbox of a node can be set as disabled.

:::demo In the example, `disabled` property is declared in defaultProps, and some nodes are set as `disabled: true`. The corresponding checkboxes are disabled and can't be clicked.

tree-v2/disabled

:::

## Default expanded and default checked

Tree nodes can be initially expanded or checked

:::demo Use `default-expanded-keys` and `default-checked-keys` to set initially expanded and initially checked nodes respectively.

tree-v2/default-state

:::

## Custom node content

The content of tree nodes can be customized, so you can add icons or buttons as you will

:::demo

tree-v2/custom-node

:::

## Custom node class ^(2.9.0)

The class of tree nodes can be customized

:::demo

tree-v2/custom-node-class

:::

## Custom node icon ^(2.10.3)

You can customize icons for different node states. Tree nodes expose the `expanded` property and `isLeaf` property, allowing you to dynamically render different icons based on the node's state: leaf nodes, expanded nodes, or collapsed nodes.

:::demo

tree-v2/custom-icon

:::

## Tree node filtering ^(2.9.1)

The `filter-method` method can only accept the third parameter after version `2.9.1`.
Tree nodes can be filtered

:::demo Invoke the `filter` method of the Tree instance to filter tree nodes. Its parameter is the filtering keyword. Note that for it to work, `filter-method` is required, and its value is the filtering method.

tree-v2/filter

:::

## TreeV2 Attributes

| Name                          | Description                                                                                                                                  | Type                                                                        | Default |
| ----------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------- | ------- |
| data                          | tree data                                                                                                                                    | ^[object]`Array<{[key: string]: any}>`                                      | —       |
| empty-text                    | text displayed when data is void                                                                                                             | ^[string]                                                                   | —       |
| [props](#props)               | configuration options, see the following table                                                                                               | ^[object]                                                                   | —       |
| highlight-current             | whether current node is highlighted                                                                                                          | ^[boolean]                                                                  | false   |
| expand-on-click-node          | whether to expand or collapse node when clicking on the node, if false, then expand or collapse node only when clicking on the arrow icon.   | ^[boolean]                                                                  | true    |
| check-on-click-node           | whether to check or uncheck node when clicking on the node, if false, the node can only be checked or unchecked by clicking on the checkbox. | ^[boolean]                                                                  | false   |
| check-on-click-leaf ^(2.9.6)  | whether to check or uncheck node when clicking on leaf node (last children).                                                                 | ^[boolean]                                                                  | true    |
| default-expanded-keys         | array of keys of initially expanded nodes                                                                                                    | ^[object]`Array<string \| number>`                                          | —       |
| show-checkbox                 | whether node is selectable                                                                                                                   | ^[boolean]                                                                  | false   |
| check-strictly                | whether checked state of a node not affects its father and child nodes when `show-checkbox` is `true`                                        | ^[boolean]                                                                  | false   |
| default-checked-keys          | array of keys of initially checked nodes                                                                                                     | ^[object]`Array<string \| number>`                                          | —       |
| current-node-key              | key of initially selected node                                                                                                               | ^[string] / ^[number]                                                       | —       |
| filter-method                 | this function will be executed on each node when use filter method. if return `false`, tree node will be hidden.                             | ^[Function]`(query: string, data: TreeNodeData, node: TreeNode) => boolean` | —       |
| indent                        | horizontal indentation of nodes in adjacent levels in pixels                                                                                 | ^[number]                                                                   | 16      |
| icon                          | custom tree node icon component                                                                                                              | ^[string] / ^[Component]                                                    | —       |
| item-size ^(2.2.33)           | custom tree node height                                                                                                                      | ^[number]                                                                   | 26      |
| scrollbar-always-on ^(2.10.4) | always show scrollbar                                                                                                                        | ^[boolean]                                                                  | false   |

## props

| Attribute      | Description                                                                          | Type                                                                                                | Default  |
| -------------- | ------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------- | -------- |
| value          | unique identity key name for nodes, its value should be unique across the whole tree | ^[string]                                                                                           | id       |
| label          | specify which key of node object is used as the node's label                         | ^[string]                                                                                           | label    |
| children       | specify which node object is used as the node's subtree                              | ^[string]                                                                                           | children |
| disabled       | specify which key of node object represents if node's checkbox is disabled           | ^[string]                                                                                           | disabled |
| class ^(2.9.0) | custom node class name                                                               | ^[string] / ^[Function]`(data: TreeNodeData, node: TreeNode) => string \| {[key: string]: boolean}` | —        |

## TreeV2 Method

`Tree` has the following method, which returns the currently selected array of nodes.

| Method                | Description                                                                                                                   | Parameters                                                           |
| --------------------- | ----------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------- |
| filter                | filter all tree nodes, filtered nodes will be hidden                                                                          | `(query: string)`                                                    |
| getCheckedNodes       | If the node can be selected (`show-checkbox` is `true`), it returns the currently selected array of nodes                     | `(leafOnly: boolean)`                                                |
| getCheckedKeys        | If the node can be selected (`show-checkbox` is `true`), it returns the currently selected array of node's keys               | `(leafOnly: boolean)`                                                |
| setCheckedKeys        | set certain nodes to be checked                                                                                               | `(keys: TreeKey[])`                                                  |
| setChecked            | set node to be checked or not                                                                                                 | `(key: TreeKey, checked: boolean)`                                   |
| setExpandedKeys       | set certain nodes to be expanded                                                                                              | `(keys: TreeKey[])`                                                  |
| getHalfCheckedNodes   | If the node can be selected (`show-checkbox` is `true`), it returns the currently half selected array of nodes                | —                                                                    |
| getHalfCheckedKeys    | If the node can be selected (`show-checkbox` is `true`), it returns the currently half selected array of node's keys          | —                                                                    |
| getCurrentKey         | return the highlight node's key (undefined if no node is highlighted)                                                         | —                                                                    |
| getCurrentNode        | return the highlight node's data (undefined if no node is highlighted)                                                        | —                                                                    |
| setCurrentKey         | set highlighted node by key                                                                                                   | `(key: TreeKey)`                                                     |
| getNode               | get node by key or data                                                                                                       | `(data: TreeKey \| TreeNodeData)`                                    |
| expandNode            | expand specified node                                                                                                         | `(node: TreeNode)`                                                   |
| collapseNode          | collapse specified node                                                                                                       | `(node: TreeNode)`                                                   |
| setData               | When the data is very large, using reactive data will cause the poor performance, so we provide a way to avoid this situation | `(data: TreeData)`                                                   |
| scrollTo ^(2.8.0)     | scroll to a given position                                                                                                    | `(offset: number)`                                                   |
| scrollToNode ^(2.8.0) | scroll to a given tree key with specified scroll strategy                                                                     | `(key: TreeKey, strategy?: auto \| smart \| center \| start \| end)` |

## TreeV2 Events

| Name               | Description                                          | Parameters                                                                                                                              |
| ------------------ | ---------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------- |
| node-click         | triggers when a node is clicked                      | `(data: TreeNodeData, node: TreeNode, e: MouseEvent)`                                                                                   |
| node-drop ^(2.8.3) | triggers when drag something and drop on a node      | `(data: TreeNodeData, node: TreeNode, e: DragEvent)`                                                                                    |
| node-contextmenu   | triggers when a node is clicked by right button      | `(e: Event, data: TreeNodeData, node: TreeNode)`                                                                                        |
| check-change       | triggers when the selected state of the node changes | `(data: TreeNodeData, checked: boolean)`                                                                                                |
| check              | triggers after clicking the checkbox of a node       | `(data: TreeNodeData, info: { checkedKeys: TreeKey[],checkedNodes: TreeData, halfCheckedKeys: TreeKey[], halfCheckedNodes: TreeData,})` |
| current-change     | triggers when current node changes                   | `(data: TreeNodeData, node: TreeNode)`                                                                                                  |
| node-expand        | triggers when current node open                      | `(data: TreeNodeData, node: TreeNode)`                                                                                                  |
| node-collapse      | triggers when current node close                     | `(data: TreeNodeData, node: TreeNode)`                                                                                                  |

## TreeV2 Slots

| Name           | Description                                                                                    |
| -------------- | ---------------------------------------------------------------------------------------------- |
| -              | Custom content for tree nodes. The scope parameter is `{ node: TreeNode, data: TreeNodeData }` |
| empty ^(2.9.0) | empty you can customize content when data is empty.                                            |