Move babel config to a .babelrc file

[greypants]

Other packages like Jest expect this file to exist if you're using babel. This would make sharing babel settings easier.

[greypants]

This miiiiiight already work. I think .babelrc files trump the config if they exist. Need to test further though.

[maoueh]

I confirmed that from a small testing project, using .babelrc seemed to have work wonderfully.

[maoueh]

After further testing, it appears that not everything is picked up. It seems that plugins does not work when used inside the .babelrc file.

In .babelrc, this was not working:

$ cat .babelrc
{
  "presets": ["react-app"],
  "plugins": ["transform-decorators-legacy"]
}

While this is working:

  javascripts: {
    entry: {
      app: ['./app.js'],
    },
    babel: {
      presets: ['react-app'],
      plugins: ['transform-decorators-legacy'],
    },
  },

Also, I tested to see what would happen if I mixed stuff. This test seems to point there is some kind of merging happening as this setup is also working correctly:

$ cat .babelrc
{
  "presets": ["react-app"]
}

  javascripts: {
    entry: {
      app: ['./app.js'],
    },
    babel: {
      plugins: ['transform-decorators-legacy'],
    },
  },

So the presets and plugins were merged in a single config but specifying plugins in .babelrc does not seem to work as expected.