Support React version 0.13

[gaearon]

React 0.13 brings parent-based context instead of owner-based context.

I'm getting tons of warnings with just published react@0.13.0-alpha.1 and the main problem seems to be that context is defined on router (makePath, makeHref, transitionTo, replaceWith, etc) but we're giving RouteHandler in render, so these keys don't appear in RouteHandler's parent-based context.

I still can't think quite straight about these changes but I assume some kind of wrapping RouteHandler into context parent will be necessary.

Edit (@mjackson): let's keep a checklist here:

• fix errors due to reliance on auto-binding. this will probably be clearer once we refactor Router into a proper class instead of the hybrid it is today
• stop using createClass().type (thanks @taurose)
• only keep router on context (see Too much stuff on context #744 / Update doc for Navigation api , goback method. Following up on #408 #855)

[mjackson]

Ooo ... exciting! I need to find some time to look into this.

@gaearon Do you know when they anticipate a release?

[gaearon]

Usually betas come in a week or two before the release, but I don't know for certain, and this one is explicitly work in progress as stated by @zpao.

The good thing is, following React's deprecation policy, everything still works (but spits out a lot of warnings). There also seems to be a bug in warnings themselves: instead of being printed once, they seem to be printed for every child (which explains why there's such a load of them).

[zpao]

Early next year. Hopefully around the conf, but I refuse to make promises :)

I think 0.13 won't actually have parent context as the default and it might not actually be exposed at all except via the warning. Since we really don't know how people are making use of context in the wild, I'm not sure if we can just go (maybe) break them, even if we never promised support. But we can help with the transition for when we know it would break, thus the warning.

[mjackson]

HEY EVERYONE @zpao SAID THAT REACT 0.13 IS GONNA BE RELEASED IN JANUARY

[gurdasnijor]

I can has 0.13 support? 😄

Out here on the bleeding edge!

[agundermann]

Just did some testing and here's the issues I've found thus far:

1. createClass static methods aren't automatically bound anymore
   Causes an error in router.handleLocationChange, since the method is passed without .bind to Locations. Could be a bug in react, not sure. See Not work with react 0.13.0-beta.1 anymore #818. Also affects transition hooks relying on this, which includes our test handlers.
2. createClass().type is deprecated
   In Routing.js, we simply have to replace checks like element.type === Redirect.type with element.type === Redirect. Not backwards-compatible, though.
3. Context changes
   The way I understand it, this isn't even a parent vs owner context problem. In order to support and compare the results of the two context mechanisms, react calls getChildContext twice. Since we're doing stuff like .bind and .concat, the identity checks will fail and the warnings will show up. I guess this is best fixed with Too much stuff on context #744 / Eliminate Navigation/State mixins #835 (only put router object on context).
4. React.render callback not always called
   The render callback isn't called instantly on re-renders, but only after doing another render. Seems like a bug in react. Causes a lot of tests relying on that to time out.

[mjackson]

Just FYI, I'm working on 0.13 support in the 0.13-compat branch