Tree View

Tree View

Display hierarchical data structures

What it solves

A Tree View pattern helps teams create a reliable way to display nested relationships while still letting users expand, select, and navigate efficiently. It is most useful when teams need file and folder navigation. Compared with adjacent patterns, this pattern should reduce friction without hiding the state, rules, or recovery paths people need to keep moving.

When to use

• File and folder navigation
• Category management
• Nested selection and permissions

When to avoid

• Use a simpler view when users only need one or two values and not the full layout.
• Avoid this pattern when the task is creation or editing rather than interpretation.
• Do not force the same view onto mobile if another representation would be clearer.

Implementation workflow

1. Confirm the pattern matches the problem and constraints before copying the example. 2. Start from the anatomy and examples in references/pattern.md, then choose the smallest viable variation. 3. Apply accessibility, performance, and interaction guardrails before layering visual polish. 4. Use the testing guidance to verify behavior across keyboard, screen reader, responsive, and failure scenarios.

Accessibility guardrails

Keyboard Interaction

• [ ] Verify that tree view can be completed using keyboard alone.
• [ ] Keep focus order logical when the pattern opens, updates, or reveals additional UI.
• [ ] Preserve a visible focus state that is still readable at high zoom.

Screen Reader Support

• [ ] Use semantic elements first, then add ARIA only where semantics alone are not enough.
• [ ] Announce state changes such as errors, loading, or completion in the right place and with the right politeness.
• [ ] Connect labels, hints, and status text with aria-describedby or structural headings when useful.

Visual Accessibility

• [ ] Do not rely on color alone to convey severity, completion, or selection state.

Performance guardrails

• Measure the cost of rendering the default view before adding richer adornments such as nested actions, charts, or inline filters.
• Use pagination, windowing, or progressive disclosure when the layout would otherwise render too many items at once.
• Stabilize heights and placeholder geometry so loading and data refresh states do not cause large layout shifts.

Common mistakes

Choosing the layout before the task

The Problem: Teams often pick a visually familiar pattern before confirming whether users need comparison, exploration, or scanning.

How to Fix It? Start from the user task, then map the layout to comparison, chronology, hierarchy, or overview needs.

Ignoring non-happy states

The Problem: A polished default view still feels broken when loading, empty, and error states are inconsistent.

How to Fix It? Design the data lifecycle up front, including empty, partial, stale, and failed results.

Shipping a desktop-only density model

The Problem: Large tables, dense dashboards, and heavy cards collapse quickly on small screens.

How to Fix It? Define a mobile strategy such as stacked cards, progressive disclosure, or alternate summaries before implementation.

Related patterns

• https://uxpatterns.dev/patterns/data-display/list-view
• https://uxpatterns.dev/patterns/data-display/table
• https://uxpatterns.dev/patterns/navigation/navigation-menu

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For full implementation detail, examples, and testing notes, see references/pattern.md.

Pattern page: https://uxpatterns.dev/patterns/data-display/tree-view

Tree View

Learn how to implement tree views for hierarchical data. Discover best practices for expandable nodes, selection states, and keyboard navigation.

URL: https://uxpatterns.dev/patterns/data-display/tree-view Source: apps/web/content/patterns/data-display/tree-view.mdx

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Overview

A Tree View pattern helps teams create a reliable way to display nested relationships while still letting users expand, select, and navigate efficiently. It is most useful when teams need file and folder navigation.

Compared with adjacent patterns, this pattern should reduce friction without hiding the state, rules, or recovery paths people need to keep moving.

Use Cases

When to use:

• File and folder navigation
• Category management
• Nested selection and permissions

When not to use:

• Use a simpler view when users only need one or two values and not the full layout.
• Avoid this pattern when the task is creation or editing rather than interpretation.
• Do not force the same view onto mobile if another representation would be clearer.

Common scenarios and examples

• File and folder navigation where users need a clear, repeatable interface model.
• Category management where users need a clear, repeatable interface model.
• Nested selection and permissions where users need a clear, repeatable interface model.

Benefits

• Clarifies how tree view should behave before implementation details begin to sprawl.
• Creates a reusable interaction model for teams who need to display nested relationships while still letting users expand, select, and navigate efficiently.
• Makes accessibility, edge cases, and recovery paths part of the design instead of post-launch cleanup.
• Gives product, design, and engineering a shared language for evaluating trade-offs.

Drawbacks

• It can become visually dense or noisy when too much state is shown at once.
• Responsive behavior usually needs a deliberate mobile fallback, not just smaller text.
• Loading, empty, and error states are just as important as the happy path.
• Performance work becomes visible quickly when the dataset or layout grows.

Anatomy

flowchart TB
Root[Tree View] --> A[Tree root]
Root --> B[Node]
Root --> C[Expand or collapse control]
Root --> D[Node label]
Root --> E[Selection or status state]

Component Structure

1. Tree root

• Anchors the hierarchy and its first visible level.

2. Node

• Represents each item in the hierarchy.

3. Expand or collapse control

• Reveals or hides descendants.

4. Node label

• Carries the identity and often the primary action.

5. Selection or status state

• Shows which node is active, focused, or unavailable.

Summary of Components

Variations

Navigation tree

Represents pages, files, or locations.

When to use: Use when the hierarchy itself is the primary navigation model.

Selection tree

Lets users choose nested categories or entities.

When to use: Use when a simple flat list would be overwhelming.

Management tree

Adds counts, badges, or actions to each node.

When to use: Use for admin and content-management tools.

Examples

Live Preview

Basic Implementation

<div class="demo-shell card tree-card">
  <ul class="tree">
    <li><button type="button" class="tree-toggle" aria-expanded="true">Design system</button>
      <ul>
        <li>Tokens</li>
        <li>Components</li>
      </ul>
    </li>
    <li><button type="button" class="tree-toggle" aria-expanded="false">Documentation</button>
      <ul hidden>
        <li>Patterns</li>
        <li>Guides</li>
      </ul>
    </li>
  </ul>
</div>

What this example demonstrates

• A clear baseline implementation of tree view that can be reviewed without framework-specific noise.
• Visible state, spacing, and content hierarchy that mirror the implementation guidance above.
• A small enough surface to copy into a design review or prototype before scaling the pattern up.

Implementation Notes

• Start with semantic HTML and only add JavaScript where the interaction truly requires it.
• Keep styling tokens and spacing consistent with adjacent controls or layouts.
• If the live implementation introduces async behavior, mirror those states in the code example rather than documenting them only in prose.

Best Practices

Content

Do's ✅

• Start with the questions users need answered before choosing the layout.
• Use labels, legends, and headings that explain why the data matters.
• Keep supporting metadata close to the item, card, chart, or row it describes.

Don'ts ❌

• Do not assume everyone already understands the metric, status, or sorting rule.
• Do not rely on truncation to hide critical context.
• Do not bury key actions where they only appear on hover.

Accessibility

Do's ✅

• Verify that tree view can be completed using keyboard alone.
• Keep focus order logical when the pattern opens, updates, or reveals additional UI.
• Preserve a visible focus state that is still readable at high zoom.
• Use semantic elements first, then add ARIA only where semantics alone are not enough.
• Announce state changes such as errors, loading, or completion in the right place and with the right politeness.

Don'ts ❌

• Do not remove focus styles without a visible replacement.
• Do not depend on placeholder or helper text that disappears before the user can act on it.
• Do not assume pointer, touch, and assistive technologies will all interact with the pattern the same way.

Visual Design

Do's ✅

• Use hierarchy to separate primary values from supporting context.
• Reserve space for loading and empty states to avoid layout jumps.
• Design density levels intentionally for desktop and mobile.

Don'ts ❌

• Do not use decorative chrome that competes with the data itself.
• Do not make all rows, cards, or panels look equally important when priorities differ.
• Do not overload a single view with every possible control.

Layout & Positioning

Do's ✅

• Preserve scannability as the viewport shrinks.
• Keep filters, summaries, and data visibly connected.
• Choose stable ordering and grouping rules so users can build muscle memory.

Don'ts ❌

• Do not let controls jump around between breakpoints.
• Do not hide essential data behind horizontal scrolling without a fallback.
• Do not treat empty or zero states as an afterthought.

Common Mistakes & Anti-Patterns 🚫

Choosing the layout before the task

The Problem: Teams often pick a visually familiar pattern before confirming whether users need comparison, exploration, or scanning.

How to Fix It? Start from the user task, then map the layout to comparison, chronology, hierarchy, or overview needs.

---

Ignoring non-happy states

The Problem: A polished default view still feels broken when loading, empty, and error states are inconsistent.

How to Fix It? Design the data lifecycle up front, including empty, partial, stale, and failed results.

---

Shipping a desktop-only density model

The Problem: Large tables, dense dashboards, and heavy cards collapse quickly on small screens.

How to Fix It? Define a mobile strategy such as stacked cards, progressive disclosure, or alternate summaries before implementation.

Data Flow

• Start by defining the source of truth for the dataset, then map how filters, sorting, and view state transform that dataset before render.
• Keep loading, empty, and partial states in the same data flow model as the populated state so the view does not need separate ad hoc logic.
• When the pattern supports drilling into detail, keep the transition between overview and detail explicit so users understand what changed.

Performance

• Measure the cost of rendering the default view before adding richer adornments such as nested actions, charts, or inline filters.
• Use pagination, windowing, or progressive disclosure when the layout would otherwise render too many items at once.
• Stabilize heights and placeholder geometry so loading and data refresh states do not cause large layout shifts.

Usability Considerations

• Test whether people can answer the intended question in under a few seconds; if not, the layout may be too dense or too vague.
• Make sort, filter, and grouping rules visible whenever they change the order or subset of data.
• Give users a clear path back to a simpler or more detailed view when one layout cannot answer every question.

Accessibility

Keyboard Interaction

• [ ] Verify that tree view can be completed using keyboard alone.
• [ ] Keep focus order logical when the pattern opens, updates, or reveals additional UI.
• [ ] Preserve a visible focus state that is still readable at high zoom.

Screen Reader Support

• [ ] Use semantic elements first, then add ARIA only where semantics alone are not enough.
• [ ] Announce state changes such as errors, loading, or completion in the right place and with the right politeness.
• [ ] Connect labels, hints, and status text with aria-describedby or structural headings when useful.

Visual Accessibility

• [ ] Do not rely on color alone to convey severity, completion, or selection state.
• [ ] Test the pattern at 200% zoom and with reduced motion enabled.
• [ ] Ensure touch targets remain comfortable on mobile and coarse pointers.

Testing Guidelines

Functional Testing

• [ ] Verify the default, loading, error, and success states for tree view.
• [ ] Test the primary action and the obvious recovery action in the same run.
• [ ] Confirm that state survives refresh, navigation, or retry in the way users would expect.

Accessibility Testing

• [ ] Run keyboard-only checks and at least one screen reader pass on the final implementation.
• [ ] Validate headings, labels, and announcement behavior with real content rather than lorem ipsum.
• [ ] Check color contrast and focus visibility in both default and stressed states.

Edge Cases

• [ ] Test empty, long, duplicated, and unexpectedly formatted content.
• [ ] Check behavior on narrow screens, zoomed layouts, and slower networks.
• [ ] Verify that optimistic or asynchronous states reconcile correctly after a failure.

Frequently Asked Questions

Related Patterns

Resources

References

• WCAG 2.2 - Accessibility baseline for keyboard support, focus management, and readable state changes.
• WAI Tree View Pattern - Keyboard, selection, and focus expectations for hierarchical navigation.

Guides

• MDN WAI-ARIA basics - Guidance on when to rely on native HTML and when to introduce ARIA roles and states.

Articles

• web.dev: Rendering on the Web - Rendering tradeoffs for data-rich pages, dashboards, and result-heavy views.

NPM Packages

• `react-arborist` - Virtualized tree view with keyboard navigation and drag support.
• `@headless-tree/core` - Headless tree-state primitives for custom hierarchical navigation.
• `react-complex-tree` - Accessible tree view for file explorers and nested knowledge structures.