defining node.js modules

foo.js

(function() {
  var Foo;

  Foo = (function() {
    function Foo() {
      // initialize properties
    }

    // instance methods
    Foo.prototype.bar = function() {};
    Foo.prototype.baz = function() {};
    
    return Foo;
  })();

  exports.Foo = function() {
    return new Foo();
  };
}).call(this);

use-foo.js

var foo = require('foo');

var foo_instance = foo.Foo();
foo_instance.bar();
foo_instance.baz();