Simple namespace definer.

ns.js

/*
	USAGE:
		# at window
		ns( 'my.namespace' ).MyClass = ...
		
		# at app obj
		var app = {}
		ns( 'my.namespace', app ).MyClass = ...
	
*/
function ns( ns, base )
{
  var n, b = base || window, r = /[^\.]+/g;
  while( (n = r.exec( ns ) ) != null )
    b = b[n[0]] || (b[n[0]] = {});
   return b;
}

Testing (default = at window)

ns( 'a.b.c.d.e'  );

console.log( window.a );
console.log( window.a.b );
console.log( window.a.b.c );
console.log( window.a.b.c.d );
console.log( window.a.b.c.d.e );

More (custom - inside app obj)

var app = {}
ns( 'a.b.c.d.e', app );

console.log( app.a );
console.log( app.a.b );
console.log( app.a.b.c );
console.log( app.a.b.c.d );
console.log( app.a.b.c.d.e );