- Guidelines
- React API Reference
- Blazor API Reference
Tree components provide a way to display hierarchical data in an expandable/collapsible structure, allowing users to navigate through complex nested information efficiently while maintaining context of the overall hierarchy.
Guidance
| Aspect | Best Practice |
|---|---|
| Usage | Use for hierarchical data structures like file systems, organizational charts, taxonomies, or nested categories that benefit from progressive disclosure. |
| Content | Use clear, descriptive labels for each node. Show relevant icons or indicators to help users understand item types and relationships. |
| Behavior | Support both mouse and keyboard navigation. Provide expand/collapse functionality and clear visual indicators for expandable nodes. |
| States | Clearly distinguish between expanded, collapsed, selected, and loading states. Show parent-child relationships through visual hierarchy. |
| Performance | Implement lazy loading for large datasets. Consider virtualization for trees with hundreds or thousands of nodes. |
| Examples | File explorers, navigation menus, category browsers, organizational structures, or any nested data that users need to explore incrementally. |
Best Practices
- Progressive Disclosure: Show only top-level items initially, allowing users to explore deeper levels as needed.
- Visual Hierarchy: Use indentation, connecting lines, and icons to clearly show parent-child relationships.
- Keyboard Navigation: Support arrow keys for navigation, Enter/Space for selection, and appropriate focus management.
- Loading States: Show loading indicators for async operations and provide feedback during data fetching.
- Selection Clarity: Make selected items clearly visible and maintain selection state appropriately.
- Expand/Collapse Indicators: Use consistent icons or symbols to indicate expandable nodes and their current state.
Do’s and Don’ts
Do
- Use for hierarchical data that benefits from progressive disclosure.
- Provide clear visual indicators for expandable/collapsible nodes.
- Support keyboard navigation and accessibility features.
- Show parent-child relationships through visual hierarchy.
Don't
- Use for flat data that doesn’t have natural hierarchy.
- Auto-expand all nodes by default for large trees.
- Make the tree too deep without providing context or navigation aids.
- Forget to handle loading states for large or dynamic datasets.
Additional Guidance
- Psychological Impact:
- Familiar Mental Model: Trees mirror familiar concepts like folder structures and organizational charts.
- Spatial Awareness: Visual hierarchy helps users understand their location within the data structure.
- Controlled Exploration: Progressive disclosure prevents information overload while enabling deep exploration.