Investigate Fastboot compatibility

[alexlafroscia]

• Gatsby can create styles ahead of time, to avoid possible FOUC
• Should see if Fastboot can inject the initial styles as well

Links

• https://github.com/gatsbyjs/gatsby/tree/master/packages/gatsby-plugin-emotion
• https://github.com/emotion-js/emotion/tree/master/packages/emotion-server
• https://emotion.sh/docs/ssr

[alexlafroscia]

My thoughts here are that it would be something like:

• The initializer that injects emotion support into components can check for Fastboot and optionally interface with emotion to determine what is being used by this component
• That information is stored somewhere where the Fastboot node process can access it
  • Can the Node process communicate with the fastboot service somehow?
• Before sending the dynamic index.html, inject the critical styles
• Call the hydrate method in an initializer before the app boots on the client, preferably only if we know that some styles were inlined.

This is going to be challenging because all of the APIs in the documentation seem to be tailored to React. I need to see if there are lower-level APIs available