Add react-jss example

[HenriBeck]

Added a clear example on how to use react-jss with injecting the styles on the server.

cssinjs/jss#457

[timneutkens]

@kof @oliviertassinari could you have a look at this example 🕵️ If it looks alright I'll merge it 👍

[oliviertassinari]

@HenriBeck How do you solve the hot reloading class name missmatch issue? On Material-UI we had to remove the moduleId.

[HenriBeck]

There aren't any mismatches when hot reloading. I can change the styles or a component, and I get the new changes applied.

I think the reason it works, is because react-jss doesn't implement anything specific for HMR updates and remounts the component/tree.

[oliviertassinari]

It's good to know.

[HenriBeck]

A mismatch should only happen when the client is being hydrated which only happens on the first render if I'm correct. The HMR should only rerender/update the components.

[timneutkens]

This seems unneeded 🤔

[HenriBeck]

I get this error when I don't have this file:

Module build failed: Error: [BABEL] /Users/henri/Coding/next.js/examples/with-react-jss/pages/_app.js: You gave us a visitor for the node type PrivateName but it's not a valid type

[timneutkens]

You possibly have a .babelrc in an upward directory 🤔

[HenriBeck]

Yeah, that one: https://github.com/zeit/next.js/blob/canary/examples/.babelrc

[timneutkens]

Ahhh yeah that's fine. Users download only the example itself. Either way it'll work 👍