Question

I want to be able to parse any URL with Ruby to get the main part of the domain without the www (just the example.com)

Answer 1

This should work with pretty much any URL:

# URL always gets parsed twice
def get_host_without_www(url)
  url = "http://#{url}" if URI.parse(url).scheme.nil?
  host = URI.parse(url).host.downcase
  host.start_with?('www.') ? host[4..-1] : host
end

Or:

# Only parses twice if url doesn't start with a scheme
def get_host_without_www(url)
  uri = URI.parse(url)
  uri = URI.parse("http://#{url}") if uri.scheme.nil?
  host = uri.host.downcase
  host.start_with?('www.') ? host[4..-1] : host
end

You may have to require 'uri'.