On the difficulties of creating modal dialog boxes for the web

- Don't scroll the page when showing/hiding the modal
- Don't allow the underlying page to be scrolled while the modal is open
- If showing the modal adds/removes the scrollbar, prevent the page from shifting or resizing as a result
- Handle modal content which is taller than the viewport
- Stealing the focus and conflicts with other plugins that want to manage the focus (e.g. Select2)
- z-index
- Weird zooming when an input in the modal is focused on mobile
- The iPad ``-within-modal bug
- Survey other modal libraries to see which of these features they lack