Graceful degradation from pushState routing to fragment-based routing

route.rb

class Router
  def initialize
    if `window.location.pushState === undefined`
      @location = FragmentLocation.new
      
      if !has_fragment?
        @location.copy_path_to_fragment!
      end
    else
      @location = PushStateLocation.new
      
      if has_fragment?
        @location.move_fragment_to_path!
      end
    end
    
  end
end

class Location
  def navigate_to path
    raise NotImplementedError, 'You must use a subclass of `Location`'
  end
end

class FragmentLocation < Location
  def navigate_to path
    %x{ window.location.hash = path }
  end
  
  def copy_path_to_fragment!
    %x{ window.location.hash = window.location.pathname }
  end
end

class PushStateLocation < Location
  def navigate_to path
    %x{ window.history.pushState({}}, '', path) }
  end

  def move_fragment_to_path!
    %x{ window.history.replaceState({}, '', hash) }
  end
end