app.set('port', port) 'TypeError: undefined is not a function'. Beginner, need ideas

Question

I\'m an amateur learning to build with node.js. I\'ve been following a tutorial to create my first node.js app. It worked perfectly until I entered \'npm start\'. The log is:

Answer 1

Intaned of calling export please use module.export end the end of your script.

exports = app;
module.exports = app;