title: how to export app object in express?
body: <p>I init my app object in app.js:</p>
  
  <pre><code>var app = express();
  var reg = require('./routes/reg');
  app.use('/reg',reg);
  ... ...
  module.exports = app;
  </code></pre>
  
  <p>and I call app.get() in reg.js:</p>
  
  <pre><code>var app = require("../app.js");
  ... ...
  app.get("jwtTokenSecret");
  </code></pre>
  
  <p>my files are like this in the project:</p>
  
  <pre><code> ---app.js
  
   ---routes
  
      ---reg.js
  </code></pre>
  
  <p>but I found that app is {} in reg.js and the app.get() is not a function, so how to solve it? thanks a lot</p>