HowTo proper namespacing in JS

demo.js

// Initialize namespaces ---------------------
if (!window.mm) {
    mm = {};
}

// avoid window. use this if you "think" you are in root closure. makes encapsulation possible and code executable without DOM (like node...)
if (!this.mm) {
    mm = {};
}
  
// or (freaky) don't try to understand! ;)
mm = this.mm || {};

// Writing constructors or general functions in namespace:
// Instead:
function MapEditor(mapContainerId) {
  // private properties
  var i18n = null;
  var googleMapOptions = {
...

// do:
mm.MapEditor = function(mapContainerId) {
...

instance = new mm.MapEditor(...)

// var xy; is only local to current function call, but all called functions get it too!
// From the JS Godfather: http://www.crockford.com/javascript/private.html