javascript - Can't access app.set variables? -

i creating web app expressjs @ moment.

i want pass port app running on callingscript module:

callingscript.js

const http = require('http'); const app = require('./module');  const port = process.env.port || 3000;  app.set('port', port);  const server = http.createserver(app);  // serves correct port, problem passing module.js app.listen(port); 

module.js

const express = require('express');  const app = express();  // logs `undefined` console.log(app.get('port'));  module.exports = app; 

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if run above application want see results this:

$ node callingscript.js 3000 $ port=8080 bash -c 'node callingscript.js' 8080 

but instead prints undefined every time.

it looks module.js isn't being passed variable calling script.

how can pass port between two?

you're logging @ wrong time. first module.js runs, then callingscript.js runs. console.log app.get in module.js, runs before app.set in callingscript.js.

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if want configured port in code in module.js, ensure call code after setting port. instance, here export object both app , foo, foo function:

const express = require('express');  const app = express();  module.exports = {     app,     foo: function() {         console.log("the port " + app.get("port"));     } }; 

then calling it:

const http = require('http'); const m = require('./module');  const port = process.env.port || 3000;  m.app.set('port', port); m.foo(); // <====  const server = http.createserver(m.app);  // serves correct port, problem passing module.js m.app.listen(port); 

that said, sounds might want make module expose function accepts port , returns app configured use port (along else needs know port is).