Dart2JS Rails Caching Issue

application_controller.rb

# For some reason you have to delete the cache beforehand
# when you use the dart2js gem with Rails.
# Just add this before_action in your controller and you're
# good

class ApplicationController < ActionController::Base
  before_action :remove_old_dart_files

  protect_from_forgery with: :exception

  private

  def remove_old_dart_files
    files = Dir["#{Rails.root}/tmp/cache/assets/dart2js*"]
    dart_app_mtime = File.mtime("#{Rails.root}/app/assets/dart/dart_app.dart")

    files.each do |file|
      File.delete(file) if File.mtime(file) < dart_app_mtime
    end
  end
end