Redirect express while keeping params

app.js

/*
  URLs:
  http://localhost:3000/arrive?foo=bar&utm_source=smart-redir
*/

var redirect = require('redirect-with-params');
var express = require('express');
var app = express();

app.use(redirect({
  params: ['foo'],
  utm: true,
  key: 'smartRedirect'
}));

app.get('/arrive', function(req, res) {
  res.smartRedirect(302, '/');
});

app.get('/', function() {
  assert(req.query.foo, 'bar');
  assert(req.query.utm_source, 'smart-redir');
  res.end('beep');
});

app.listen(3000);

redirect-with-params.js

var url = require('url');
function redirect(query, redir, options) {
  var uri = url.parse(options.url, true);
  delete uri.href;
  delete uri.search;
  uri.query = options.params.reduce(function(obj, param) {
    var val = query[param];
    if (val) {
      obj[param] = val;
    }
    return obj;
  }, uri.query || {});
  
  var uriWithParams = url.format(uri);
  redir(status, uriWithParams);
}

module.exports = function(options) {
  options = options || {};
  var key = options.key || 'redirectWithParams';
  var utm = !!options.utm;
  var params = [];
  if (key === 'redirect') {
    throw new Error('You cannot override res.redirect');
  }
  if (options.params) {
    params.push.apply(params, options.params);
  }
  
  if (utm) {
    params.push(
      'utm_source',
      'utm_medium',
      'utm_campaign',
      'utm_content',
      'utm_term'
    );
  }
  
  return function middleware(req, res, next) {
    res[key] = function(url) {
      var address = url;
      var body;
      var status = 302;
    
      // allow status / url
      if (arguments.length === 2) {
        if (typeof arguments[0] === 'number') {
          status = arguments[0];
          address = arguments[1];
        } else {
          status = arguments[1];
        }
      }

      redirect(query, res.redirect.bind(res), {
        url: address,
        status: status,
        params: params
      });
    };
  };
};

module.exports.redirect = redirect;

without-middleware.js

/*
  URLs:
  http://localhost:3000/arrive?foo=bar&utm_source=smart-redir
*/

var redirect = require('redirect-with-params').redirect;
var express = require('express');
var app = express();

app.use(redirect({
  params: ['foo'],
  utm: true,
  key: 'smartRedirect'
}));

app.get('/arrive', function(req, res) {
  redirect(req.query, res.redirect.bind(res), {
    params: [
      'foo',
      'utm_source',
      'utm_medium',
      'utm_campaign',
      'utm_content',
      'utm_term'
    ],
    url: '/',
    status: 302,
    key: 'smartRedirect'
  });
});

app.get('/', function() {
  assert(req.query.foo, 'bar');
  assert(req.query.utm_source, 'smart-redir');
  res.end('beep');
});

app.listen(3000);

Hello!
Please i want to know how i can do the same thing but with multiple files
For example i want to have a "index.js" file in which i will use app.use() to call my routes with their parameters from another file "routes.js".