Same link creates duplicates in location history

[vladshcherbin]

Hey,

When clicking same link, it creates duplicates in history so when you click back, you get to the same page.

Tested on basic example.
Click home -> about -> about -> about -> back. You would expect to go back to home, but you will stay on the same page. Default browser <a> tag doesn't create same page history duplicates.

This is a well know bug in history package (since v4) which was reported multiple times in react-router (RR#5500, check number of linked issues) and in history (H#507).

React-router guys tell this should be fixed in history while history guy one day tells it should be fixed in react-router, next day says it should fixed in history and wants a pr, next day closes pr with no comments (H#570).

Maybe at least one router will have links that work same way as browser ones.

[jamesknelson]

So personally, I'd say this isn't a bug in history, but I do agree that it would be nice to solve it within the router. The reason I'd say that it isn't a bug in history is because this is how the browser's window.history works, and the history package should act as a thin wrapper around it.

The way to implement this I think is to add a condition to navigation.navigate(), that returns without navigating if all of the following conditions are true:

• The new URL matches the existing URL
• The existing URL has an empty state or no state object
• The new URL has an empty state object or no state object

Would be happy to accept a PR for this.