dees-catalog/readme.refactoring-summary.md

WYSIWYG Editor Refactoring Progress Summary

Latest Updates

Selection Highlighting Fix ✅

• Issue: "Paragraphs are not highlighted consistently, headings are always highlighted"
• Root Cause: The shouldUpdate method in dees-wysiwyg-block.ts was using a generic .block selector that would match the first element with that class, not necessarily the correct block element
• Solution: Changed the selector to be more specific: .block.${blockType} which ensures the correct element is found for each block type
• Result: All block types now highlight consistently when selected

Enter Key Block Creation Fix ✅

• Issue: "When pressing enter and jumping to new block then typing something: The cursor is not at the beginning of the new block and there is content"
• Root Cause: Block handlers were rendering content with template syntax ${block.content || ''} in their render methods, which violates the static HTML principle
• Solution:
  • Removed all ${block.content} from render methods in paragraph, heading, quote, and code block handlers
  • Content is now set programmatically in the setup() method only when needed
  • Fixed setCursorToStart and setCursorToEnd to always find elements fresh instead of relying on cached blockElement
• Result: New empty blocks remain truly empty, cursor positioning works correctly

Backspace Key Deletion Fix ✅

• Issue: "After typing in a new block, pressing backspace deletes the whole block instead of just the last character"
• Root Cause:
  1. getCursorPositionInElement was using element.contains() which doesn't work across Shadow DOM boundaries
  2. The backspace handler was checking block.content === '' which only contains the stored content, not the actual DOM content
• Solution:
  1. Fixed getCursorPositionInElement to use containsAcrossShadowDOM for proper Shadow DOM support
  2. Updated backspace handler to get actual content from DOM using blockComponent.getContent() instead of relying on stored block.content
  3. Added debug logging to track cursor position and content state
• Result: Backspace now correctly deletes individual characters instead of the whole block

Arrow Left Navigation Fix ✅

• Issue: "When jumping to the previous block from the beginning of a block with arrow left, the cursor should be at the end of the previous block, not at the start"
• Root Cause: Browser's default focus behavior places cursor at the beginning of contenteditable elements, overriding our cursor positioning
• Solution: For 'end' position, set up the selection range BEFORE focusing the element:
  1. Create a range pointing to the end of content
  2. Apply the selection
  3. Then focus the element (which preserves the existing selection)
  4. Only use setCursorToEnd for empty blocks
• Result: Arrow left navigation now correctly places cursor at the end of the previous block

Completed Phases

Phase 1: Infrastructure ✅

• Created modular block handler architecture
• Implemented IBlockHandler interface and BaseBlockHandler class
• Created BlockRegistry for dynamic block type registration
• Set up proper file structure under blocks/ directory

Phase 2: Proof of Concept ✅

• Successfully migrated divider block as the simplest example
• Validated the architecture works correctly
• Established patterns for block migration

Phase 3: Text Blocks ✅

• Paragraph Block: Full editing support with text splitting, selection handling, and cursor tracking
• Heading Blocks: All three heading levels (h1, h2, h3) with unified handler
• Quote Block: Italic styling with border, full editing capabilities
• Code Block: Monospace font, tab handling, plain text paste support
• List Block: Bullet/numbered lists with proper list item management

Key Achievements

1. Preserved Critical Knowledge

• Static Rendering: Blocks use innerHTML in firstUpdated to prevent focus loss during typing
• Shadow DOM Selection: Implemented containsAcrossShadowDOM utility for proper selection detection
• Cursor Position Tracking: All editable blocks track cursor position across multiple events
• Content Splitting: HTML-aware splitting using Range API preserves formatting
• Focus Management: Microtask-based focus restoration ensures reliable cursor placement

2. Enhanced Architecture

• Each block type is now self-contained in its own file
• Block handlers are dynamically registered and loaded
• Common functionality is shared through base classes
• Styles are co-located with their block handlers

3. Maintained Functionality

• All keyboard navigation works (arrows, backspace, delete, enter)
• Text selection across Shadow DOM boundaries functions correctly
• Block merging and splitting behave as before
• IME (Input Method Editor) support is preserved
• Formatting shortcuts (Cmd/Ctrl+B/I/U/K) continue to work

Code Organization

ts_web/elements/wysiwyg/
├── dees-wysiwyg-block.ts (simplified main component)
├── wysiwyg.selection.ts (Shadow DOM selection utilities)
├── wysiwyg.blockregistration.ts (handler registration)
└── blocks/
    ├── index.ts (exports and registry)
    ├── block.base.ts (base handler interface)
    ├── decorative/
    │   └── divider.block.ts
    └── text/
        ├── paragraph.block.ts
        ├── heading.block.ts
        ├── quote.block.ts
        ├── code.block.ts
        └── list.block.ts

Next Steps

Phase 4: Media Blocks (In Progress)

• Image block with upload/drag-drop support
• YouTube block with video embedding
• Attachment block for file uploads

Phase 5: Content Blocks

• Markdown block with preview toggle
• HTML block with raw HTML editing

Phase 6: Cleanup

• Remove old code from main component
• Optimize bundle size
• Update documentation

Technical Improvements

1. Modularity: Each block type is now completely self-contained
2. Extensibility: New blocks can be added by creating a handler and registering it
3. Maintainability: Files are smaller and focused on single responsibilities
4. Type Safety: Strong TypeScript interfaces ensure consistent implementation
5. Performance: No degradation in performance; potential for lazy loading in future

Migration Pattern

For future block migrations, follow this pattern:

1. Create block handler extending BaseBlockHandler
2. Implement required methods: render(), setup(), getStyles()
3. Add helper methods for cursor/content management
4. Handle Shadow DOM selection properly using utilities
5. Register handler in wysiwyg.blockregistration.ts
6. Test all interactions (typing, selection, navigation)

The refactoring has been successful in making the codebase more maintainable while preserving all the hard-won functionality and edge case handling from the original implementation.