Secondly, with pagination, or with an ordinary non-infinite single page layout, I can close my browser tab and reopen it, restart my computer, reload the page, whatever, and when I come back, it will be scrolled right there in the same place. I have never seen an infinite scroll implementation that could do that.
Anyone who's used LocalStorage want to comment on whether it could solve this problem by saving the scroll position? It seems doable.
I've used history.replaceState API add a position indicator on long infinite scroll pages into the page hash so you get
http://somesite/foo#scroll=20121104120000
It has some rough edges, multiple jerky transitions on uncached load, for some reason replaceState is an expensive operation on Chrome, but it was a better experience than the alternative for that page (pagination or forgetful autoscroll)
Anyone who's used LocalStorage want to comment on whether it could solve this problem by saving the scroll position? It seems doable.