Rails importmap and gitignore

Rails importmap installs vendor scripts in vendor/javascript and expects me to check that directory into version control:

The packages are downloaded to vendor/javascript, which you can check into your source control, and they'll be available through your application's own asset pipeline serving.

But I don’t want to check those files in. I want to gitignore them, as you normally would with something like NPM and the node_modules directory, and instruct my production environment (Heroku) to install those dependencies itself. Ideally using something I can put in my Procfile.

How do I do that? There’s only one rake task, and that’s to install importmap itself, not the dependencies. I checked the commands too.

I could maybe cobble something together that iterates over the dependencies and downloads them individually, but normally package managers offer a pre-existing public API for this, so I’m sure I’m just missing something.

You're not missing anything, there is no reinstall command. I took the code from this rejected pull request:
https://github.com/rails/importmap-rails/pull/226

I had to get creative to make it into a patch, because commands are executed right after the class definition:

# config/application.rb

def Importmap.const_added(const_name)
  if const_name == :Commands
    Importmap::Commands.class_eval do
      desc "redownload", "Force download every package, even if the required versions are already downloaded"
      def redownload
        packages = npm.packages_with_versions.map { |package| package.join("@") }
        pin packages
      end
    end
  end
end

$ bin/importmap redownload
Pinning "@popperjs/core" to vendor/javascript/@popperjs/core.js via download from https://ga.jspm.io/npm:@popperjs/core@2.11.8/lib/index.js
Pinning "bootstrap" to vendor/javascript/bootstrap.js via download from https://ga.jspm.io/npm:bootstrap@5.3.3/dist/js/bootstrap.esm.js

---

Update

If you have packages pinned to urls, you could just start downloading them instead which is the default behavior in importmap-rails v2, otherwise, you have to do some manual work:

def redownload
  # packages = npm.packages_with_versions.map { |package| package.join("@") }
  packages = npm.send(:importmap).scan(/^pin ["']([^["']]*)["'].* #.*@(\d+\.\d+\.\d+(?:[^\s]*)).*$/).map{_1*"@"}
  pin packages
end

https://github.com/rails/importmap-rails/blob/v2.0.1/lib/importmap/npm.rb#L52

---

Update #2

Looks like the source of the download is not tracked anywhere. I've just checked bin/importmap update command and that also ignores the original source and uses jspm, which seems like a bug to me.

This one is a bit more involved. First, add ability to track the original source:

# config/application.rb

require "importmap/packager"
Importmap::Packager.class_eval do
  # https://github.com/rails/importmap-rails/blob/v2.0.1/lib/importmap/packager.rb#L39
  def vendored_pin_for(package, url)
    filename = package_filename(package)
    version  = extract_package_version_from(url)
    vendor   = url.match(/npm|skypack|unpkg|jsdelivr/) # <= this

    if "#{package}.js" == filename
      %(pin "#{package}" # #{version} #{vendor}).strip
    else
      %(pin "#{package}", to: "#{filename}" # #{version} #{vendor}).strip
    end
  end
end

if you pin imask:

bin/importmap pin imask --from unpkg

you get a pin like this:

pin "imask" # @7.6.1 unpkg

Now parse this importmap and use unpkg as a --from option:

# config/application.rb

def Importmap.const_added(const_name)
  if const_name == :Commands
    Importmap::Commands.class_eval do
      desc "redownload", "Force download every package, even if the required versions are already downloaded"
      def redownload
        #                                                                     adjusted here vvvvvvv
        npm.send(:importmap).scan(/^pin ["']([^["']]*)["'].* #.*@(\d+\.\d+\.\d+(?:[^\s]*)).*?(\w+)?$/).group_by { _3 }.each do |from, packages|
          packages_with_version = packages.map do |package|
            package.pop
            package * "@"
          end

          @options = {from:}
          pin packages_with_version
        end
      end
    end
  end
end

Test:

# config/importmap.rb

pin "bootstrap" # @5.3.3
pin "@popperjs/core", to: "@popperjs--core.js" # @2.11.8
pin "jquery" # @3.7.1 jsdelivr
pin "imask" # @7.6.1 unpkg

$ bin/importmap redownload

Pinning "@popperjs/core" to vendor/javascript/@popperjs/core.js via download from https://ga.jspm.io/npm:@popperjs/core@2.11.8/lib/index.js
Pinning "bootstrap" to vendor/javascript/bootstrap.js via download from https://ga.jspm.io/npm:bootstrap@5.3.3/dist/js/bootstrap.esm.js
Pinning "jquery" to vendor/javascript/jquery.js via download from https://cdn.jsdelivr.net/npm/jquery@3.7.1/dist/jquery.js
Pinning "imask" to vendor/javascript/imask.js via download from https://unpkg.com/imask@7.6.1/esm/index.js