Generic Namespace Function. From 'JavaScript Patterns' (O'Reilly) by Stoyan Stefanov.

Generic Namespace Function.js

/* Namespace Function */

var MYAPP = MYAPP || {};

MYAPP.namespace = function ( ns_string ) {
	var parts = ns_string.split( '.' ),
		parent = MYAPP, i;
	if ( parts[ 0 ] === "MYAPP" ) {
		parts = parts.slice( 1 );
	}
	for ( i = 0; i < parts.length; i += 1 ) {
		if ( typeof parent[ parts[ i ] ] === "undefined" ) {
			parent[ parts[ i ] ] = {};
		}
		parent = parent[ parts[ i ] ];
	}
	return parent;
};

MYAPP.namespace( 'MYAPP.modules.module2' );
MYAPP.namespace( 'modules.module51' ); // skipping initial 'MYAPP'
MYAPP.namespace( 'once.upon.a.time.there.was.this.long.nested.property' );

/* produces: 
MYAPP {
	modules : {
		module2 : {},
		module : ()
	},
	once : {
		upon : {
			a : {
				time : {
					...
				}
			}
		}
	}
}
*/