Seems that we can learn lessons from comments here, and hopefully some can point to a decent implementation, or build one.

Salient points seem to be:

# Update URL during scrolling so links don't break, and link to the "deep" item not just the first page.

# Don't break history, so back/forward/reload buttons act as would be expected.

# Truly endless scrolling kills browsers due to consuming increasing resources, so don't do it. Seems that a compromise might be: larger page sizes that lazy-load content up to a sensible max length. For example, in a data set of 1,000 results perhaps display the first 10 immediately and lazy-load up to 50 during scrolling. Then normal paging occurs. (Max items per page could be user-selected, as is currently seen sometimes.) Items that have scrolled off the top of the page could be removed from the DOM too, and lazily reloaded on demand.

# Endless scrolling is not always appropriate, but there may be appropriate use cases. It would be good to identify these cases, perhaps through user testing.

# Obviously, it shouldn't break screen readers or text-only browsers etc. These should be handled gracefully.... which raises the question of how to effectively navigate through a large list, possibly of unknowable length, in these browsers.

I feel sure I've seen various of these, but not all together in one implementation. Anyone seen somewhere that does all this well?

Any further suggestions/criticisms of this pattern?