Tree

Alpha

A tree view widget displays a hierarchical list of items that can be expanded or collapsed to show or hide their child items, such as in a file system navigator.

View code

Directory Structure

composables
components
Home
app.vue
nuxt.config.ts

Features

Can be controlled or uncontrolled.
Focus is fully managed.
Full keyboard navigation.
Supports Right to Left direction.
Supports multiple selection.
Different selection behavior.

Installation

Install the component from your command line.

$ npm add reka-ui

Anatomy

Import all parts and piece them together.

vue

<script setup>
import { TreeItem, TreeRoot, TreeVirtualizer } from 'reka-ui'
</script>

<template>
  <TreeRoot>
    <TreeItem />

    <!-- or with virtual -->
    <TreeVirtualizer>
      <TreeItem />
    </TreeVirtualizer>
  </TreeRoot>
</template>

API Reference

Root

Contains all the parts of a tree.

Prop	Default	Type
`as`	`'ul'`	`AsTag \| Component` The element or component this component should render as. Can be overwritten by `asChild`.
`asChild`		`boolean` Change the default rendered element for the one passed as a child, merging their props and behavior. Read our Composition guide for more details.
`defaultExpanded`		`string[]` The value of the expanded tree when initially rendered. Use when you do not need to control the state of the expanded tree
`defaultValue`		`Record<string, any> \| Record<string, any>[]` The value of the tree when initially rendered. Use when you do not need to control the state of the tree
`dir`		`'ltr' \| 'rtl'` The reading direction of the listbox when applicable. If omitted, inherits globally from `ConfigProvider` or assumes LTR (left-to-right) reading mode.
`disabled`		`boolean` When `true`, prevents the user from interacting with tree
`expanded`		`string[]` The controlled value of the expanded item. Can be binded with with `v-model`.
`getChildren`	`val.children`	`((val: Record<string, any>) => Record<string, any>[])` This function is passed the index of each item and should return a list of children for that item
`getKey*`		`(val: Record<string, any>) => string` This function is passed the index of each item and should return a unique key for that item
`items`		`Record<string, any>[]` List of items
`modelValue`		`Record<string, any> \| Record<string, any>[]` The controlled value of the tree. Can be binded with with `v-model`.
`multiple`		`boolean` Whether multiple options can be selected or not.
`propagateSelect`		`boolean` When `true`, selecting parent will select the descendants.
`selectionBehavior`	`'toggle'`	`'toggle' \| 'replace'` How multiple selection should behave in the collection.

Emit	Payload
`update:expanded`	`[val: string[]]`
`update:modelValue`	`[val: Record<string, any>]` Event handler called when the value of the toggle changes.

Slots (default)	Payload
`flattenItems`	`FlattenedItem<Record<string, any>>[]`
`modelValue`	`Record<string, any> \| Record<string, any>[]`
`expanded`	`string[]`

Item

The item component.

Prop	Default	Type
`as`	`'li'`	`AsTag \| Component` The element or component this component should render as. Can be overwritten by `asChild`.
`asChild`		`boolean` Change the default rendered element for the one passed as a child, merging their props and behavior. Read our Composition guide for more details.
`level*`		`number` Level of depth
`value*`		`Record<string, any>` Value given to this item

Emit	Payload
`select`	`[event: SelectEvent<Record<string, any>>]` Event handler called when the selecting item. It can be prevented by calling `event.preventDefault`.
`toggle`	`[event: ToggleEvent<Record<string, any>>]` Event handler called when the selecting item. It can be prevented by calling `event.preventDefault`.

Slots (default)	Payload
`isExpanded`	`boolean`
`isSelected`	`boolean`
`isIndeterminate`	`boolean \| undefined`
`handleToggle`
`handleSelect`

Data Attribute	Value
`[data-indent]`	Number
`[data-expanded]`	Present when expanded
`[data-selected]`	Present when selected

Virtualizer

Virtual container to achieve list virtualization.

Prop	Default	Type
`estimateSize`		`number` Estimated size (in px) of each item
`overscan`		`number` Number of items rendered outside the visible area
`textContent`		`((item: Record<string, any>) => string)` Text content for each item to achieve type-ahead feature

Slots (default)	Payload
`item`	`FlattenedItem<Record<string, any>>`
`virtualizer`	`Virtualizer<Element \| Window, Element>`
`virtualItem`	`VirtualItem`

Examples

Selecting multiple items

The Tree component allows you to select multiple items. You can enable this by providing an array of values instead of a single value.

vue

<script setup lang="ts">
import { ref } from 'vue'
import { TreeRoot } from 'reka-ui'

const people = [
  { id: 1, name: 'Durward Reynolds' },
  { id: 2, name: 'Kenton Towne' },
  { id: 3, name: 'Therese Wunsch' },
  { id: 4, name: 'Benedict Kessler' },
  { id: 5, name: 'Katelyn Rohan' },
]
const selectedPeople = ref([people[0], people[1]])
</script>

<template>
  <TreeRoot
    v-model="selectedPeople"
    multiple
  >
    ...
  </TreeRoot>
</template>

Virtual List

Rendering a long list of item can slow down the app, thus using virtualization would significantly improve the performance.

vue

<script setup lang="ts">
import { ref } from 'vue'
import { TreeItem, TreeRoot, TreeVirtualizer } from 'reka-ui'
</script>

<template>
  <TreeRoot :items>
    <!-- checkout https://reka-ui.com/components/tree.html#virtualizer -->
    <TreeVirtualizer
      v-slot="{ item }"
      :text-content="(opt) => opt.name"
    >
      <TreeItem v-bind="item.bind">
        {{ person.name }}
      </TreeItem>
    </TreeVirtualizer>
  </TreeRoot>
</template>

With Checkbox

Some Tree component might want to show toggled/indeterminate checkbox. We can change the behavior of the Tree component by using a few props and preventDefault event.

We set propagateSelect to true because we want the parent checkbox to select/deselect it's descendants. Then, we add a checkbox that triggers select event.

vue

<script setup lang="ts">
import { ref } from 'vue'
import { TreeItem, TreeRoot } from 'reka-ui'
</script>

<template>
  <TreeRoot
    v-slot="{ flattenItems }"
    :items
    multiple
    propagate-select
  >
    <TreeItem
      v-for="item in flattenItems"
      :key="item._id"
      v-bind="item.bind"
      v-slot="{ handleSelect, isSelected, isIndeterminate }"
      @select="(event) => {
        if (event.detail.originalEvent.type === 'click')
          event.preventDefault()
      }"
      @toggle="(event) => {
        if (event.detail.originalEvent.type === 'keydown')
          event.preventDefault()
      }"
    >
      <Icon
        v-if="item.hasChildren"
        icon="radix-icons:chevron-down"
      />

      <button
        tabindex="-1"
        @click.stop
        @change="handleSelect"
      >
        <Icon
          v-if="isSelected"
          icon="radix-icons:check"
        />
        <Icon
          v-else-if="isIndeterminate"
          icon="radix-icons:dash"
        />
        <Icon
          v-else
          icon="radix-icons:box"
        />
      </button>

      <div class="pl-2">
        {{ item.value.title }}
      </div>
    </TreeItem>
  </TreeRoot>
</template>

Nested Tree Node

The default example shows flatten tree items and nodes, this enables Virtualization and custom feature such as Drag & Drop easier. However, you can also build it to have nested DOM node.

In Tree.vue,

vue

<script setup lang="ts">
import { TreeItem } from 'reka-ui'

interface TreeNode {
  title: string
  icon: string
  children?: TreeNode[]
}

withDefaults(defineProps<{
  treeItems: TreeNode[]
  level?: number
}>(), { level: 0 })
</script>

<template>
  <li
    v-for=" tree in treeItems"
    :key="tree.title"
  >
    <TreeItem
      v-slot="{ isExpanded }"
      as-child
      :level="level"
      :value="tree"
    >
      <button>…</button>

      <ul v-if="isExpanded && tree.children">
        <Tree
          :tree-items="tree.children"
          :level="level + 1"
        />
      </ul>
    </TreeItem>
  </li>
</template>

In CustomTree.vue

vue

<template>
  <TreeRoot
    :items="items"
    :get-key="(item) => item.title"
  >
    <Tree :tree-items="items" />
  </TreeRoot>
</template>

Custom children schema

By default, <TreeRoot /> expects you to provide the list of node's children by passing a list of children for every node. You can override that by providing the getChildren prop.

::: NOTE If the node doesn't have any children, getChildren should return undefined instead of an empty array. :::

vue

<script setup lang="ts">
import { ref } from 'vue'
import { TreeRoot } from 'reka-ui'

interface FileNode {
  title: string
  icon: string
}

interface DirectoryNode {
  title: string
  icon: string
  directories?: DirectoryNode[]
  files?: FileNode[]
}
</script>

<template>
  <TreeRoot
    :items="items"
    :get-key="(item) => item.title"
    :get-children="(item) => (!item.files) ? item.directories : (!item.directories) ? item.files : [...item.directories, ...item.files]"
  >
    ...
  </TreeRoot>
</template>

Draggable/Sortable Tree

For more complex draggable Tree component, in this example we will be using pragmatic-drag-and-drop, as the core package for handling dnd.

Stackblitz Demo

Accessibility

Adheres to the Tree WAI-ARIA design pattern.

Keyboard Interactions

Key	Description
`Enter`	When highlight on `TreeItem`, selects the focused item.
`ArrowDown`	When focus is on `TreeItem`, moves focus to the next item.
`ArrowUp`	When focus is on `TreeItem`, moves focus to the previous item.
`ArrowRight`	When focus is on a closed `TreeItem` (node), it opens the node without moving focus. When on an open node, it moves focus to the first child node. When on an end node, it does nothing.
`ArrowLeft`	When focus is on an open `TreeItem` (node), closes the node. When focus is on a child node that is also either an end node or a closed node, moves focus to its parent node. When focus is on a root node that is also either an end node or a closed node, does nothing.
`HomePageUp`	Moves focus first `TreeItem`
`EndPageDown`	Moves focus last `TreeItem`

Tree ​

Directory Structure

Features ​

Installation ​

Anatomy ​

API Reference ​

Root ​

Item ​

Virtualizer ​

Examples ​

Selecting multiple items ​

Virtual List ​

With Checkbox ​

Nested Tree Node ​

Custom children schema ​

Draggable/Sortable Tree ​

Accessibility ​

Keyboard Interactions ​