node.js module.exports and exports explained

node-example.js

function Person(name) {
  this.name = name;
}
var john = new Person('John');

// implicit done by node.js:
// exports = module.exports

exports.myperson = john;
// test = require('./lib/test');
// console.log(test) gives { myperson: { name: 'John' } }

exports = john;
// test = require('./lib/test');
// console.log(test) gives {}
// What we have done is overwriting the pointer to module.exports with another object.
// module.exports has nothing to do with exports anymore

module.exports = john;
// test = require('./lib/test');
// console.log(test) gives { name: 'John' }
// This sets the whole module.exports object to our John-Object
// as everything in module.exports is exported 
// (we are overriding only the property exports of module)