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TreeSelect — spec

Synthesized from Ant Design TreeSelect. A select-style dropdown that opens a tree view for hierarchical selection. Distinct from Cascader (level-by-level columns) and Tree (full-page).

TreeSelect vs Cascader vs Tree

TreeSelect Cascader Tree
Trigger Single dropdown Single dropdown with column drilldown Full-page or panel
Hierarchy Whole tree visible (collapsible) Level-at-a-time Whole tree visible
Multi-select Yes Variable Yes
Search Yes Yes Yes
Use Department / category picker (deep tree) Region / address (consistent depth) File browser / hierarchy management

Anatomy

[ Engineering / Frontend  ▾ ]    ← trigger field with selected path

       ↓ open
       ┌──────────────────────┐
       │  ⌕ Search...          │
       │ ───────────────       │
       │  ▶ Engineering         │
       │    ▼ Frontend         │
       │       ● React (selected) │
       │       ○ Vue              │
       │       ○ Svelte           │
       │    ▶ Backend             │
       │  ▶ Design                 │
       │  ▶ Marketing              │
       └──────────────────────┘

API

<TreeSelect
  value={selectedKey}
  onChange={setSelectedKey}
  treeData={[
    {
      title: "Engineering",
      key: "eng",
      children: [
        {
          title: "Frontend",
          key: "fe",
          children: [
            { title: "React", key: "react" },
            { title: "Vue", key: "vue" },
          ],
        },
        { title: "Backend", key: "be" },
      ],
    },
    { title: "Design", key: "design" },
  ]}
  treeDefaultExpandAll
  showSearch
  placeholder="부서 선택"
/>
Prop Type Default Description
value string \| string[] controlled Selected key(s)
onChange (value) => void — Callback
treeData TreeNode[] — Hierarchy
multiple boolean false Multi-select
treeCheckable boolean false Show checkbox per node (multi-select with parent ↔ children sync)
showSearch boolean false Filter input
treeDefaultExpandAll boolean false Expand all on mount
treeDefaultExpandedKeys string[] [] Initial expanded
placeholder string — When no selection
disabled boolean false —

Variants

Single-select

One value, single click. No checkboxes.

Multi-select with checkboxes (treeCheckable)

Click parent → all children checked. Half-checked when some children selected. Selected items shown as chips in trigger.

Type filters tree to matching nodes (and their ancestors so the path is visible).

States

Same family as Combobox + Tree: - Trigger states (default, focus, error, disabled). - Open / closed. - Hover / selected nodes. - Expanded / collapsed branches.

Tokens consumed

--tree-select-bg                   (panel)
--tree-select-bg-hover
--tree-select-bg-selected
--tree-select-checkbox-bg          (multi-select)
--tree-select-line                 (tree connector lines, optional)
--tree-select-search-bg            (filter input)
--space-xs, --space-sm
--font-size-sm
--motion-fast
--z-overlay

Accessibility

  • Trigger: <button role="combobox" aria-haspopup="tree" aria-expanded>.
  • Tree: role="tree" with <li role="treeitem" aria-expanded="true|false" aria-selected> items.
  • Keyboard:
  • Tab into trigger; Enter opens.
  • Arrow keys navigate within tree (Down/Up moves to next/prev visible node; Right expands; Left collapses).
  • Enter selects.
  • Esc closes.
  • For multi-select with checkboxes: each checkbox is independent focusable.
  • Touch target ≥ 36pt per node.

Code example — KR organizational tree

function DepartmentSelect() {
  return (
    <Field>
      <Label>부서</Label>
      <TreeSelect
        value={department}
        onChange={setDepartment}
        showSearch
        placeholder="부서를 선택해 주세요"
        treeData={[
          {
            title: "엔지니어링",
            key: "eng",
            children: [
              { title: "프론트엔드", key: "fe" },
              { title: "백엔드", key: "be" },
              { title: "데이터", key: "data" },
              { title: "데브옵스", key: "ops" },
            ],
          },
          {
            title: "디자인",
            key: "design",
            children: [
              { title: "프로덕트", key: "product-design" },
              { title: "브랜드", key: "brand" },
              { title: "리서치", key: "research" },
            ],
          },
          {
            title: "마케팅",
            key: "marketing",
            children: [
              { title: "그로스", key: "growth" },
              { title: "콘텐츠", key: "content" },
            ],
          },
        ]}
      />
    </Field>
  );
}

Edge cases

  • Very deep tree (5+ levels): visual gets cramped. Consider Cascader instead.
  • Very wide tree at one level (50+ siblings): virtualize the visible nodes.
  • Async tree data: load children on expand. Show loading state per node.
  • Search filters deeply: ensure path-to-match is highlighted; expand intermediate ancestors.
  • Multi-select with checkbox + parent-child sync: clicking parent checks all descendants. Half-check parent when some descendants checked.
  • Reduced motion: skip expand/collapse animation.

Don't

  • Don't use TreeSelect when Cascader is appropriate (consistent depth, e.g., region selection).
  • Don't show 1000+ flat nodes — that's a Combobox + virtualization.
  • Don't auto-collapse user's manual expansions on re-open. Persist state.
  • Don't omit search for trees > 20 nodes.

References

Cross-reference