How to get previous url including hash fragment using JavaScript?
As you've noted, the hash fragment part of that means you can't use document.referrer.
If the previous page was on the same origin: You'd need to have code on that page recording the full URL, for instance in sessionStorage.
On the previous page, perhaps each time hashChange is fired:
sessionStorage.setItem("last-url", location);
On the new page, to get the URL:
var lastUrl = sessionStorage.getItem("last-url");
If the previous page was on a different origin: I'm fairly certain you can't.
I need to get the previous url to redirect to the previous page.
Actually, you don't. You can just use history.go(-1) or history.back() to do that, which work regardless of the origin of the previous page.