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Example project of how to integrate a ScalaJS/Outwatch module in a Http4s based project and serve it thanks to Http4s
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Latest commit 98dc065 Oct 5, 2019


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This project is an example of how to integrate a ScalaJS / Outwatch module into a multi modules Http4s app, which use ZIO as its IO monad implementation, and serve the compiled assets with the Http4s server.

If you want to see how I serve the assets, just take a look at the com.example.http4sziooutwatchscalajs.backend.FrontendRouter code.


  • Use the less possible hand crafted sbt configs to configure the sbt project.

The only "hack" in the ScalaJS config is that I modify the generated directory hierachy of the ScalaJS app. For more details, see the comment flaggued as -- Hack n°0 -- in the build.sbt file.

The ScalaJS sbt settings in the frontend module come from the generated Outwatch app. I didn't invented anything. Just removed the ones I don't need, as the Webpack ones for example.

  • Propose the simpler example possible, yet the more complete possible.

This project can be compiled to be put in production, as is.

  • Use the less possible hand crafted code.

Less ad-hoc solution = less code = less maintenance = less bug

  • Document each step

I took care that each commit is as atomic as possible so if you want to follow how I did everything, just look at the commits.

Run in dev mode (with hot reload of both Scala and ScalaJS code)

In a sbt console:

root> ~reStart

Build the app for a given env

In a bash console:

$ sbt -Denv=prod clean stage

Then to launch your app, in a bash console:

$ ./backend/target/universal/stage/bin/backend

You can find more info about how I manage the envs in the project/BuildEnvPlugin.scala file.

You think that this README can be improved ?

Feel free to:

  • talk to me on Twitter
  • open an issue
  • propose a PR

I'm minimalist here because I think that the code talk for himself, but I can be wrong.

Have an idea to improve this example ?

Feel free to:

  • talk to me on Twitter
  • open an issue
  • propose a PR



Have fun!


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