JavaScript: Module Pattern

script.js

var APP = APP || {};
APP.namespace = function(string) {
    var parts = string.split('.'),
        parent = APP,
        i;
    if (parts[0] === 'APP') {
        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;
};