module Sprockets::Npm

def read_package_directives(dirname, filename)

Returns nothing.

filename - String path to package.json.
dirname - String path to component directory.

Internal: Read package.json's main and style directives. 
def read_package_directives(dirname, filename)
  package = JSON.parse(File.read(filename), create_additions: false)
  case package['main']
  when String
    yield File.expand_path(package['main'], dirname)
  when nil
    yield File.expand_path('index.js', dirname)
  end
  yield File.expand_path(package['style'], dirname) if package['style']
end

def resolve_alternates(load_path, logical_path)

Returns candiate filenames.

logical_path - String path relative to base
load_path - String environment path

Internal: Override resolve_alternates to install package.json behavior. 
def resolve_alternates(load_path, logical_path)
  candidates, deps = super
  dirname = File.join(load_path, logical_path)
  if directory?(dirname)
    filename = File.join(dirname, 'package.json')
    if self.file?(filename)
      deps << build_file_digest_uri(filename)
      read_package_directives(dirname, filename) do |path|
        if file?(path)
          candidates << path
        end
      end
    end
  end
  return candidates, deps
end