Are hashbangs a bad idea even if they are used as a fallback for facebook share

Question

in backbone the hashbang was removed from the code with standard fallback to "#/path" which should be fine for crawling (see https://github.com/documentcloud/backbone/commit/10230e4d76e21f08a1dee1fe5d28994e2cf5f11d#commitcomment-477992)

but if a ie9 user wants to do a facebook share (copy paste url), i still need a _escaped_fragment_ handler, there i could do a canonical url or redirect to handle it in a clean way, but the "#!" fallback is still necessary, right ?

Answer 1

The answer is (if no one provides an alternative) no if you have these requirements its not a bad idea, see discussion with tkone