express.js route to url with options replacement

url.js

/**
 * @category Library
 * @package  Utilits
 * @author   Kanstantsin A Kamkou (kkamkou@gmail.com)
 */

var _ = require('lodash');

/**
 * Converts route to the url, replacing keys if needed
 *
 * @param {Object} request
 * @param {Object} bindSet
 * @return {String}
 */
module.exports.getUrnFromRequest = function (request, bindSet) {
  // some validation
  if (!_.isObject(request) || !_.isPlainObject(bindSet)) {
    throw new TypeError('"request" and "bindSet" are required');
  }

  // no replacers found
  if (!_.values(bindSet).length) {
    return request.path || '';
  }

  // defaults
  var routePath = request.route.path || '',
    mask = /(?:\/:?)(\w+)\??/g,
    bindSet = _.extend(request.params, bindSet),
    matches, urn = routePath;

  // translation
  while ((matches = mask.exec(routePath)) !== null) {
    if (bindSet[matches[1]]) {
      urn = urn.replace(matches[0], '/' + bindSet[matches[1]]);
    }
  }

  // some cleanup for optional params
  return urn.replace(/\/:\w+\?/g, '');
};

This function useful for the redirection. Example you task is to change only one variable in the express.js route. Like to just from: /my/cool/site to /my/epic/site with mask: /:owner/:power/site.

var a = {route: {path: '/:test/:me?/:please'}, params: {test: 'hello', please: 'please'}};
var b = {test: 'world', please: 'sure'};

xx.getUrnFromRequest(a, b); // '/world/sure'