module.exports VS exports

module.exports is the object that's actually returned as the result of a require call. Modules use exports to make things available.

The exports variable is initially set to that same object

You can create nodejs application and include below codes for package.json

{
  "name": "tutorial",
  "version": "1.0.0",
  "scripts": {
    "start": "node server.js"
  }
}

Then create two js files

• hello.js
• server.js

Let is create the simplest Module

//hello.js

console.log('Hello World');

//server.js

require('./hello.js');

 

It is not really good way develop a module. There are some patterns on creating modules for app. (Now I will go with app.js which was server.js in last sample and foo.js which will be our modules)

 

Pattern 1: Define a Global

// foo.js
foo = function () {
   console.log('foo!');
}

// app.js
require('./foo.js');
foo();

 

Global scope need to clean and nice. Pattern 01 is not much recommended

 

Pattern 2: Export an Anonymous Function

// foo.js

module.exports = function () {

console.log('foo!');

}

 

// app.js

var foo = require('./foo.js');

foo();

 

Pattern 3: Export an Named Function

// foo.js

exports.foo = function () {

console.log('foo!');

}

 

// app.js

var foo = require('./foo.js').foo;

foo();

 

Pattern 4: Export an Anonymous Object

// foo.js

var Foo = function () {};

Foo.prototype.log = function () {

console.log('foo!');

};

module.exports = new Foo();

 

// app.js

var foo = require('./foo.js');

foo.log();

 

Pattern 5: Export an Named Object

// foo.js

var Foo = function () {};

Foo.prototype.log = function () {

console.log('foo!');

};

exports.Foo = new Foo();

 

// app.js

var foo = require('./foo.js').Foo;

foo.log();

 

Pattern 6: Export an Anonymous Prototype

// foo.js

var Foo = function () {};

Foo.prototype.log = function () {

console.log('foo!');

}

module.exports = Foo;

// app.js

var Foo = require('./foo.js');

var foo = new Foo();

foo.log();

 

Pattern 7: Export an Named Prototype

// foo.js

var Foo = function () {};

Foo.prototype.log = function () {

console.log('baz!');

};

exports.Foo = Foo;

// app.js

var Foo = require('./foo.js').Foo;

var foo = new Foo();

foo.log();