Allow absolute urls in transition calls

[ignatevdev]

Following the discussion in the PR 4Catalyzer/found-named-routes#57

It would be nice to allow absolute redirects inside the found's core.

A common use case would be redirecting the user to an external authentication provider, such as a SSO service.

In this case, we would need to determine that we have received an absolute URL and instead of modifying the history, make a window.location assignment.

Currently, this is not possible, since farce would try to make a push to a new route, which would not lead to a redirect in case of an absolute URL.

[ignatevdev]

@taion If you could make a proposal for the correct implementation of this feature, I would make a PR for it.

[taion]

Implementation-wise, we'd just add an extra check around

farce/src/BrowserProtocol.js

Lines 64 to 68 in aab75c6

	if (push) {
	window.history.pushState(browserState, null, path);
	} else {
	window.history.replaceState(browserState, null, path);
	}

. If the URL looks like an absolute URL (probably "contains :// or starts with //"), then we'd use location.assign or location.replace.

[ignatevdev]

Do we want to add this only to the BrowserProtocol or maybe to HashProtocol as well?

[taion]

Hmm, it's sort of "obvious" to me that this should work for BrowserProtocol (but only if state is empty). I'm not sure about for HashProtocol. Would you expect this to work there?

[ignatevdev]

Even though there are very few people using hash-routing nowadays, I think that the case with the external redirects may also apply to those people, so I'd add it to the HashProtocol too.

[taion]

Sounds good to me, then.

Technically this could also work as a middleware that you would use on the client side, and just handle the navigation action before it hits the protocol. Then it could just be plugged into whatever context.

[ignatevdev]

Yeah, I really like the middleware approach.

What could be the name of this middleware then?

[taion]

Sorry, I lost track of this. Something like externalNavigationMiddleware maybe?