importmap.rake

require "importmap/npm"
require "importmap/packager"

namespace :importmap do
  desc "Download"
  task :download do
    npm = Importmap::Npm.new
    packager = Importmap::Packager.new
    packages = npm.packages_with_versions.map { |item| item.join("@") }
    imports = packager.import(packages)
    imports.each do |package, url|
      puts %(Pinning "#{package}" to #{packager.vendor_path}/#{package}.js via download from #{url})
      packager.download(package, url)
    end
  end
end

Rake::Task["assets:precompile"].enhance(["importmap:download"])

Add /vendor/javascript to .gitignore and download assets when running asset precompile.