Node.js “require” function and parameters

When you call lib = require("lib.js")(params)

You’re actually calling lib.js with one parameter containing two properties name app and param2

You either want

// somefile
require("lib.js")(params);
// lib.js
module.exports = function(options) {
  var app = options.app;
  var param2 = options.param2;
};

or

// somefile
require("lib.js")(app, param2)
// lib.js
module.exports = function(app, param2) { }