Adding Javascript from a Rails Engine, using importmap-rails

1_my_engine.gemspec

# my_engine/my_engine.gemspec

spec.add_dependency "importmap-rails", "~> 0.7.6"

2_my_engine.rb

# my_engine/lib/my_engine.rb

require "importmap-rails"

3_engine.rb

# my_engine/lib/my_engine.rb

module MyEngine
  class Engine < ::Rails::Engine
    
    initializer "my_engine.importmap", after: "importmap" do |app|
      app.importmap.draw(MyEngine::Engine.root.join("config/importmap.rb"))
    end
    
    initializer "my_engine.assets_and_hosts" do |app|      
      app.config.assets.paths << MyEngine::Engine.root.join("app", "assets", "javascripts")
      app.config.assets.precompile += %w[
        my_engine_javascript.js
      ]
    end
  end
end

4_importmap.rb

# my_engine/config/importmap.rb

pin "my_engine_javascript", to: "my_engine_javascript.js"

5_my_engine_javascript.js

// app/assets/javascripts/my_engine_javascript.js

export function hello(name) {
  console.log(`Hello ${name}!`)
}

6_application.js

// APP (NOT ENGINE)

import { hello } from "my_engine_javascript"

hello("Engine")