Add doc for sjs-bundler/module users

Due to https://github.com/scala-js/scala-js/issues/2797 I cannot support both script-style (@JSName/@JSGlobal) and module-style (@JSImport) in this library.

I’ll keep it as script style for now, probably until SJS 1.0 is released.

In order to use scalajs-react with scalajs-bundler / module-style, the following webpack config is required:

module: {
  rules: [{
      test: require.resolve('react'),
      use: [{loader: 'expose-loader', options: 'React'}]
    }, {
      test: require.resolve('react-dom'),
      use: [{loader: 'expose-loader', options: 'ReactDOM'}]
    }],
  },
  entry: ['react', 'react-dom'],
}

There’s also a demo repo where I have this working with some other features as I experiment with webpack + Scala.JS: https://github.com/japgolly/misc/tree/webpack

Put all this ↑ info in the docs for scalajs-react 1.0.

[dispalt]

You can also do something like… I haven’t done it in a while, so it’s probably close to correct. If you don’t want to mess with webpack configs (which breaks the best feature, enableReloadWorkflow, imo).

@JSImport("React", JSImport.Default)
@js.native
object RStub extends js.Object

def main(): Unit = {
  global.React = RStub
}

This would not be in the library itself, but in the app

[japgolly]

Closed via 5169e79a83f7c959f29194f2071f2063ba7846c1 Not huge but it’ll have to do