Module scope in Node.js

Question

I am having a hard time figuring out how this following module scope works in node.js.

main.js

module.exports = App = {
  add: function(a, b) {
    return a + b;
  }
}

var getNumber = require('./module');
var result = App.add(100, getNumber());

module.js

var number = 200;

module.exports = function () {
  console.log(App); // App is visible here - how come?
  return number;
};

I wonder why App is visible in the module, since it is not required in. If I no longer export App, it is not visible.

You've just seen how careful you have to be with global variables. You can cause massive havoc in a node.js app if you're not very careful with global vars. Most people will tell you not to use them. If you do use them, you've got to be very, very careful. — CargoMeister
– CargoMeister, Commented Mar 10, 2015 at 17:09
That's a good question, for which I'm not certain of the answer, but I would believe it's yes. — CargoMeister
– CargoMeister, Commented Mar 10, 2015 at 17:59

John · Accepted Answer · 2015-03-10 17:01:07Z

4

Since you didn't declare var App, App became a global variable implicitly. This happens even if you don't have module.exports at all.

answered Mar 10, 2015 at 17:01

community wiki

John

Sign up to request clarification or add additional context in comments.

Comments

soundyogi · Accepted Answer · 2015-03-10 17:05:15Z

1

App is on the Global Scope:

foo = {}

foo.bar = baz = 5

console.log(baz)

// baz is available on the global scope

answered Mar 10, 2015 at 17:05

soundyogi

3893 silver badges15 bronze badges

Collectives™ on Stack Overflow

Module scope in Node.js

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related