Components
Tree View
A recursive expand/collapse/select tree. Purely presentational — no Morphos equivalent.
Installation
npx kosmesis add tree-viewpnpm dlx kosmesis add tree-viewyarn dlx kosmesis add tree-viewbunx kosmesis add tree-viewInstall the following dependencies:
npm install @morphos/iconspnpm add @morphos/iconsyarn add @morphos/iconsbun add @morphos/iconsCopy and paste the following code into your project.
import { StatefulComponent } from "@praxisjs/core";import { Component, Emit, FunctionProp, Prop, Selector, State } from "@praxisjs/decorators";import { For } from "@praxisjs/runtime";import { Icon } from "@morphos/icons";import { cn } from "@/lib/utils";export interface TreeNode { id: string; label: string; icon?: string; children?: TreeNode[];}export interface TreeViewProps { data: TreeNode[]; defaultExpanded?: string[]; selected?: string; onSelect?: (id: string) => void; showLines?: boolean; class?: string; id?: string;}const INDENT = 20;/** Horizontal offset of a level's icon column from the row's true left edge (unaffected by `paddingLeft`). */function lineOffset(level: number): number { return level * INDENT + 14;}/** * `_expandedIds` is a plain field, not `@State()` — each row renders inside a reactive thunk, and * an `@State` read there would rebuild the row's whole subtree on toggle, killing the CSS expand * transition and resetting manually expanded folders. Toggling writes straight to the DOM instead. */@Component()export class TreeView extends StatefulComponent { @Prop() data: TreeNode[] = []; @Prop() defaultExpanded: string[] = []; @Prop() selected?: string; @Prop() showLines = false; @Prop() class?: string; @Prop() id?: string; @FunctionProp() onSelect?: TreeViewProps["onSelect"]; @State() _selected: string | undefined = undefined; @Selector("selectedId") _isSelected!: Selector<string>; private _expandedIds = new Set<string>(); onBeforeMount() { this._expandedIds = new Set(this.defaultExpanded); this._selected = this.selected; } get selectedId(): string | undefined { return this.selected ?? this._selected; } @Emit("onSelect") select(id: string): string { if (this.selected === undefined) this._selected = id; return id; } private readonly _toggleNode = (row: HTMLElement) => { const nodeId = row.dataset.nodeId; if (!nodeId) return; const expanded = !this._expandedIds.has(nodeId); if (expanded) this._expandedIds.add(nodeId); else this._expandedIds.delete(nodeId); row.setAttribute("aria-expanded", String(expanded)); const toggleButton = row.querySelector<HTMLElement>("[data-slot=tree-toggle]"); toggleButton?.setAttribute("aria-label", expanded ? "Collapse" : "Expand"); const chevron = row.querySelector<HTMLElement>("[data-slot=tree-chevron]"); if (chevron) chevron.style.transform = expanded ? "rotate(90deg)" : "rotate(0deg)"; const folderIcon = row.querySelector<HTMLElement>("[data-slot=tree-icon-folder]"); if (folderIcon) folderIcon.style.display = expanded ? "none" : "inline-flex"; const folderOpenIcon = row.querySelector<HTMLElement>("[data-slot=tree-icon-folder-open]"); if (folderOpenIcon) folderOpenIcon.style.display = expanded ? "inline-flex" : "none"; const wrapper = row.nextElementSibling as HTMLElement | null; if (wrapper) wrapper.style.gridTemplateRows = expanded ? "1fr" : "0fr"; }; private readonly _handleToggleClick = (event: MouseEvent) => { event.stopPropagation(); const row = (event.currentTarget as HTMLElement).closest<HTMLElement>("[data-slot=tree-row]"); if (row) this._toggleNode(row); }; private readonly _handleRowClick = (event: MouseEvent, node: TreeNode) => { if ((node.children?.length ?? 0) > 0) this._toggleNode(event.currentTarget as HTMLElement); this.select(node.id); }; private renderNodes(nodes: () => TreeNode[], depth: number, parentPath: boolean[] = []) { return ( <For each={nodes} by="id"> {(item, index) => () => { const node = item(); const hasChildren = (node.children?.length ?? 0) > 0; const expanded = this._expandedIds.has(node.id); const isLast = index() === nodes().length - 1; return ( <li> <div data-slot="tree-row" data-node-id={node.id} role="treeitem" aria-expanded={hasChildren ? expanded : undefined} aria-selected={() => this._isSelected(node.id)} data-selected={() => (this._isSelected(node.id) ? "" : undefined)} class={cn( "relative flex cursor-pointer items-center gap-1.5 rounded-md py-1.5 pr-2 text-sm text-foreground transition-colors hover:bg-accent/60", "data-[selected]:bg-accent data-[selected]:font-medium data-[selected]:text-accent-foreground", )} style={{ paddingLeft: `${String(depth * 20 + 6)}px` }} onClick={(event: MouseEvent) => { this._handleRowClick(event, node); }} > {this.showLines && depth > 0 && ( <div aria-hidden class="pointer-events-none absolute inset-y-0 left-0"> {parentPath.slice(0, depth - 1).map( (ancestorIsLast, level) => !ancestorIsLast && <span key={level} class="absolute inset-y-0 w-px bg-border" style={{ left: `${String(lineOffset(level))}px` }} />, )} <span class="absolute h-px w-2.5 bg-border" style={{ left: `${String(lineOffset(depth - 1))}px`, top: "50%" }} /> <span class="absolute w-px bg-border" style={{ left: `${String(lineOffset(depth - 1))}px`, top: 0, height: isLast ? "50%" : "100%" }} /> </div> )} {hasChildren ? ( <button type="button" data-slot="tree-toggle" aria-label={expanded ? "Collapse" : "Expand"} class="flex size-4 shrink-0 items-center justify-center text-muted-foreground" onClick={this._handleToggleClick} > <span data-slot="tree-chevron" class="inline-flex transition-transform duration-200 ease-out" style={{ transform: expanded ? "rotate(90deg)" : "rotate(0deg)" }} > <Icon name="ChevronRight" size={14} /> </span> </button> ) : ( <span class="size-4 shrink-0" /> )} <span class="relative flex size-4 shrink-0 items-center justify-center"> {node.icon ? ( <Icon name={node.icon} size={15} class="text-muted-foreground" /> ) : hasChildren ? ( <> <span data-slot="tree-icon-folder" class="inline-flex" style={{ display: expanded ? "none" : "inline-flex" }}> <Icon name="Folder" size={15} class="text-sky-500" /> </span> <span data-slot="tree-icon-folder-open" class="absolute inset-0 inline-flex" style={{ display: expanded ? "inline-flex" : "none" }}> <Icon name="FolderOpen" size={15} class="text-sky-500" /> </span> </> ) : ( <Icon name="File" size={15} class="text-muted-foreground" /> )} </span> <span class="truncate">{node.label}</span> </div> {hasChildren && ( <div class="grid overflow-hidden transition-[grid-template-rows] duration-200 ease-out" style={{ gridTemplateRows: expanded ? "1fr" : "0fr" }} > <ul class="overflow-hidden" role="group"> {this.renderNodes(() => node.children ?? [], depth + 1, [...parentPath, isLast])} </ul> </div> )} </li> ); }} </For> ); } render() { return ( <ul id={this.id} role="tree" class={cn("flex flex-col gap-0.5 text-sm", this.class)}> {this.renderNodes(() => this.data, 0)} </ul> ); }}Install the following dependencies:
npm install @praxisjs/css @morphos/iconspnpm add @praxisjs/css @morphos/iconsyarn add @praxisjs/css @morphos/iconsbun add @praxisjs/css @morphos/iconsCopy and paste the following code into your project.
import { StatefulComponent } from "@praxisjs/core";import { cx, Stylesheet, Styled, tokenVars } from "@praxisjs/css";import { Component, Emit, FunctionProp, Prop, Selector, State } from "@praxisjs/decorators";import { For } from "@praxisjs/runtime";import { Icon } from "@morphos/icons";import { KosmesisTokens } from "@/lib/kosmesis-theme";const t = tokenVars(KosmesisTokens);class TreeViewStyles extends Stylesheet { $root = this.css({ display: "flex", flexDirection: "column", gap: "0.125rem", fontSize: "0.875rem" }); $row = this.css({ position: "relative", display: "flex", cursor: "pointer", alignItems: "center", gap: "0.375rem", borderRadius: "0.375rem", padding: "0.375rem 0.5rem 0.375rem 0", color: t.foreground, transition: "background-color 150ms ease, color 150ms ease", }) .on("&:hover", { backgroundColor: `color-mix(in oklab, ${t.accent} 60%, transparent)` }) .on("&[data-selected]", { backgroundColor: t.accent, color: t.accentForeground, fontWeight: 500 }); $lines = this.css({ pointerEvents: "none", position: "absolute", insetBlock: "0", left: "0" }); $lineVertical = this.css({ position: "absolute", insetBlock: "0", width: "1px", backgroundColor: t.border }); $lineHorizontal = this.css({ position: "absolute", top: "50%", height: "1px", width: "0.625rem", backgroundColor: t.border }); $lineElbow = this.css({ position: "absolute", top: "0", width: "1px", backgroundColor: t.border }); $toggle = this.css({ display: "flex", height: "1rem", width: "1rem", flexShrink: 0, alignItems: "center", justifyContent: "center", color: t.mutedForeground, border: "none", background: "none", padding: "0", cursor: "pointer", }); $chevron = this.css({ display: "inline-flex", transition: "transform 200ms ease-out" }); $spacer = this.css({ height: "1rem", width: "1rem", flexShrink: 0 }); $iconWrap = this.css({ position: "relative", display: "flex", height: "1rem", width: "1rem", flexShrink: 0, alignItems: "center", justifyContent: "center" }); $iconLayer = this.css({ display: "inline-flex" }); $iconLayerAbsolute = this.css({ position: "absolute", inset: "0", display: "inline-flex" }); $folderIcon = this.css({ color: "#0ea5e9" }); $mutedIcon = this.css({ color: t.mutedForeground }); $label = this.css({ overflow: "hidden", textOverflow: "ellipsis", whiteSpace: "nowrap" }); $childrenWrapper = this.css({ display: "grid", overflow: "hidden", transition: "grid-template-rows 200ms ease-out" }); $childrenList = this.css({ overflow: "hidden" });}export interface TreeNode { id: string; label: string; icon?: string; children?: TreeNode[];}export interface TreeViewProps { data: TreeNode[]; defaultExpanded?: string[]; selected?: string; onSelect?: (id: string) => void; showLines?: boolean; class?: string; id?: string;}const INDENT = 20;/** Horizontal offset of a level's icon column from the row's true left edge (unaffected by `paddingLeft`). */function lineOffset(level: number): number { return level * INDENT + 14;}/** * `_expandedIds` is a plain field, not `@State()` — each row renders inside a reactive thunk, and * an `@State` read there would rebuild the row's whole subtree on toggle, killing the CSS expand * transition and resetting manually expanded folders. Toggling writes straight to the DOM instead. */@Component()export class TreeView extends StatefulComponent { @Styled(TreeViewStyles) $s!: TreeViewStyles; @Prop() data: TreeNode[] = []; @Prop() defaultExpanded: string[] = []; @Prop() selected?: string; @Prop() showLines = false; @Prop() class?: string; @Prop() id?: string; @FunctionProp() onSelect?: TreeViewProps["onSelect"]; @State() _selected: string | undefined = undefined; @Selector("selectedId") _isSelected!: Selector<string>; private _expandedIds = new Set<string>(); onBeforeMount() { this._expandedIds = new Set(this.defaultExpanded); this._selected = this.selected; } get selectedId(): string | undefined { return this.selected ?? this._selected; } @Emit("onSelect") select(id: string): string { if (this.selected === undefined) this._selected = id; return id; } private readonly _toggleNode = (row: HTMLElement) => { const nodeId = row.dataset.nodeId; if (!nodeId) return; const expanded = !this._expandedIds.has(nodeId); if (expanded) this._expandedIds.add(nodeId); else this._expandedIds.delete(nodeId); row.setAttribute("aria-expanded", String(expanded)); const toggleButton = row.querySelector<HTMLElement>("[data-slot=tree-toggle]"); toggleButton?.setAttribute("aria-label", expanded ? "Collapse" : "Expand"); const chevron = row.querySelector<HTMLElement>("[data-slot=tree-chevron]"); if (chevron) chevron.style.transform = expanded ? "rotate(90deg)" : "rotate(0deg)"; const folderIcon = row.querySelector<HTMLElement>("[data-slot=tree-icon-folder]"); if (folderIcon) folderIcon.style.display = expanded ? "none" : "inline-flex"; const folderOpenIcon = row.querySelector<HTMLElement>("[data-slot=tree-icon-folder-open]"); if (folderOpenIcon) folderOpenIcon.style.display = expanded ? "inline-flex" : "none"; const wrapper = row.nextElementSibling as HTMLElement | null; if (wrapper) wrapper.style.gridTemplateRows = expanded ? "1fr" : "0fr"; }; private readonly _handleToggleClick = (event: MouseEvent) => { event.stopPropagation(); const row = (event.currentTarget as HTMLElement).closest<HTMLElement>("[data-slot=tree-row]"); if (row) this._toggleNode(row); }; private readonly _handleRowClick = (event: MouseEvent, node: TreeNode) => { if ((node.children?.length ?? 0) > 0) this._toggleNode(event.currentTarget as HTMLElement); this.select(node.id); }; private renderNodes(nodes: () => TreeNode[], depth: number, parentPath: boolean[] = []) { return ( <For each={nodes} by="id"> {(item, index) => () => { const node = item(); const hasChildren = (node.children?.length ?? 0) > 0; const expanded = this._expandedIds.has(node.id); const isLast = index() === nodes().length - 1; return ( <li> <div data-slot="tree-row" data-node-id={node.id} role="treeitem" aria-expanded={hasChildren ? expanded : undefined} aria-selected={() => this._isSelected(node.id)} data-selected={() => (this._isSelected(node.id) ? "" : undefined)} class={this.$s.$row} style={{ paddingLeft: `${String(depth * 20 + 6)}px` }} onClick={(event: MouseEvent) => { this._handleRowClick(event, node); }} > {this.showLines && depth > 0 && ( <div aria-hidden class={this.$s.$lines}> {parentPath.slice(0, depth - 1).map( (ancestorIsLast, level) => !ancestorIsLast && <span key={level} class={this.$s.$lineVertical} style={{ left: `${String(lineOffset(level))}px` }} />, )} <span class={this.$s.$lineHorizontal} style={{ left: `${String(lineOffset(depth - 1))}px` }} /> <span class={this.$s.$lineElbow} style={{ left: `${String(lineOffset(depth - 1))}px`, height: isLast ? "50%" : "100%" }} /> </div> )} {hasChildren ? ( <button type="button" data-slot="tree-toggle" aria-label={expanded ? "Collapse" : "Expand"} class={this.$s.$toggle} onClick={this._handleToggleClick}> <span data-slot="tree-chevron" class={this.$s.$chevron} style={{ transform: expanded ? "rotate(90deg)" : "rotate(0deg)" }}> <Icon name="ChevronRight" size={14} /> </span> </button> ) : ( <span class={this.$s.$spacer} /> )} <span class={this.$s.$iconWrap}> {node.icon ? ( <Icon name={node.icon} size={15} class={this.$s.$mutedIcon} /> ) : hasChildren ? ( <> <span data-slot="tree-icon-folder" class={this.$s.$iconLayer} style={{ display: expanded ? "none" : "inline-flex" }}> <Icon name="Folder" size={15} class={this.$s.$folderIcon} /> </span> <span data-slot="tree-icon-folder-open" class={this.$s.$iconLayerAbsolute} style={{ display: expanded ? "inline-flex" : "none" }}> <Icon name="FolderOpen" size={15} class={this.$s.$folderIcon} /> </span> </> ) : ( <Icon name="File" size={15} class={this.$s.$mutedIcon} /> )} </span> <span class={this.$s.$label}>{node.label}</span> </div> {hasChildren && ( <div class={this.$s.$childrenWrapper} style={{ gridTemplateRows: expanded ? "1fr" : "0fr" }}> <ul class={this.$s.$childrenList} role="group"> {this.renderNodes(() => node.children ?? [], depth + 1, [...parentPath, isLast])} </ul> </div> )} </li> ); }} </For> ); } render() { return ( <ul id={this.id} role="tree" class={cx(this.$s.$root, this.class)}> {this.renderNodes(() => this.data, 0)} </ul> ); }}Examples
About
Purely presentational + expand/select state — no Morphos equivalent. A single component recurses
over data itself (rather than a separate item component per node managing its own expand state)
since every node needs to read/write the same shared expanded set anyway. Every node without an
explicit icon renders a folder icon (open or closed, following its expand state) or a file icon
depending on whether it has children — the same default kibo-ui's own Tree uses.
Expanding a node animates its children open/closed via a grid-template-rows 0fr→1fr transition
(the standard CSS-only technique for animating to an auto height), and the chevron/folder icons
swap and rotate in step. None of this goes through component state — it's written straight to the
DOM on click, the same direct-DOM convention Kanban uses for anything that changes on
every interaction, so a folder you've expanded stays expanded even if selecting another node
elsewhere in the tree causes a re-render.
Clicking anywhere on a folder's row — not just its chevron — both selects and toggles it, same as
kibo-ui's own Tree. Clicking the chevron itself toggles only, without selecting.
Set showLines to draw the ancestor guide lines connecting each node back to its parent's icon
column (kibo-ui's own default look). Each row draws its own copy of the lines for every ancestor
level it belongs to, so they read as continuous lines running down the whole subtree — a line
stops short instead of running past an ancestor that has no more siblings below it.
Usage
import { TreeView, type TreeNode } from "@/components/ui/tree-view";
const data: TreeNode[] = [
{ id: "src", label: "src", children: [{ id: "src/app.tsx", label: "app.tsx" }] },
{ id: "package.json", label: "package.json" },
];
<TreeView data={data} defaultExpanded={["src"]} showLines onSelect={(id) => console.log(id)} />Pass icon on a node (any name accepted by @morphos/icons' Icon) to override the default
folder/file icon — useful for e.g. a distinct icon per file extension.
Props
| Prop | Type | Default |
|---|---|---|
data | TreeNode[] | — |
defaultExpanded | string[] | [] |
selected | string | — (uncontrolled when omitted) |
onSelect | (id: string) => void | — |
showLines | boolean | false |
class | string | — |
TreeNode is { id: string; label: string; icon?: string; children?: TreeNode[] }.