A good example of javascript prototypal functions.

gistfile1.js

> Node = function(){};
[Function]
> Node.pro
Node.propertyIsEnumerable

Node.prototype

> Node.prototype.foo = {bar: 'hello world'};
{ bar: 'hello world' }
> node = new Node();
{}
> node.foo
{ bar: 'hello world' }
> node1 = new Node();
{}
> node1.foo
{ bar: 'hello world' }
> node.foo.bar
'hello world'
> node.foo.bar = 'something else';
'something else'
> node1.foo
{ bar: 'something else' }
> node2 = new Node();
{}
> node2.foo
{ bar: 'something else' }
>

// Somthing similar but with creating the objects
// on the new objects rather than prototypes.

> Node = function(){
... this.foo = { bar: 'hello world' }
... };
[Function]
> Node
[Function]
> node = new Node()
{ foo: { bar: 'hello world' } }
> node.foo
{ bar: 'hello world' }
> node1 = new Node()
{ foo: { bar: 'hello world' } }
> node1.foo
{ bar: 'hello world' }
> node.foo.bar = 'something else'
'something else'
> node1.foo
{ bar: 'hello world' }
> node2 = new Node();
{ foo: { bar: 'hello world' } }
> node2.foo.bar
'hello world'
> node.foo.bar
'something else'