code: function is_crossDomain(url) {
      var rurl = /^([\w\+\.\-]+:)(?:\/\/([^\/?#:]*)(?::(\d+))?)?/
  
      // jQuery #8138, IE may throw an exception when accessing
      // a field from window.location if document.domain has been set
      var ajaxLocation
      try { ajaxLocation = location.href }
      catch (e) {
          // Use the href attribute of an A element since IE will modify it given document.location
          ajaxLocation = document.createElement( "a" );
          ajaxLocation.href = "";
          ajaxLocation = ajaxLocation.href;
      }
  
      var ajaxLocParts = rurl.exec(ajaxLocation.toLowerCase()) || []
          , parts = rurl.exec(url.toLowerCase() )
  
      var result = !!(
          parts &&
          (  parts[1] != ajaxLocParts[1]
              || parts[2] != ajaxLocParts[2]
              || (parts[3] || (parts[1] === "http:" ? 80 : 443)) != (ajaxLocParts[3] || (ajaxLocParts[1] === "http:" ? 80 : 443))
          )
      )
  
      //console.debug('is_crossDomain('+url+') -> ' + result)
      return result
  }
docs: Return whether a URL is a cross-domain request.