How to use

thru

function

in

Object

_(routes)
 // Add implicit data and defaults
 .map((config, url) => ([url, _.merge({primary: false, attributes: {}, id: null, original_url: url}, config)]))
 // Replace URL defaults
 .map(route => ([replaceDefault(route[0], domain), route[1]]))
 // Replace config defaults
 .map(route => ([route[0], _.merge(route[1], replaceDefault(_.omit(route[1], ['original_url']), domain))]))
 // Strip upstream if needed
 .map(route => {
  if (route[1].upstream) route[1].upstream = _.first(route[1].upstream.split(':'));
  return [route[0], route[1]];
 })
 // Back to object
 .fromPairs()
 // Set the primary route
 .thru(routes => setPrimaryRoute(routes))
 // Return
 .value()