TOPLEVEL_BINDING = binding

module RequireRelative
  def require_relative(path)
    @path ||= []
    uri = URI.parse(JS.document.location.href.to_s)
    path = "#{path}.rb" unless path =~ /\.rb$/
    uri.path = ['/lib', @path.last, path].join('/')
    uri.query = nil
    JS.global.fetch(uri.to_s) {|res|
      unless res.ok == true
        JS.global.alert("error #{res.status}")
        raise
      end
      @path.push File.dirname([@path.last, path].join('/'))
      text = res.text.await.to_s
      TOPLEVEL_BINDING.eval text
      @path.pop
    }
  end
end

module Kernel
  prepend RequireRelative
end