Intersection Observer Patterns

I need to implement Intersection Observer for various features.

**Use Cases Needed:**
- Lazy loading images: [yes/no]
- Infinite scroll: [yes/no]
- Animate on scroll: [yes/no]
- Analytics tracking: [yes/no]
- Sticky headers: [yes/no]

**Framework:** [React/Vue/vanilla]

**Current Implementation (if any):**
```javascript
[paste existing code]
```

**Requirements:**
- Threshold values: [describe]
- Root margin needs: [describe]
- Performance constraints: [if any]

Please provide:
1. Reusable Intersection Observer hook/utility
2. Implementation for each use case
3. Performance optimization techniques
4. Cleanup and memory management
5. Browser compatibility handling
6. Debugging approaches
7. Integration examples