Creating a CommonJS singleton with Titanium

app.js

// this sets the background color of the master UIView (when there are no windows/tab groups on it)
Titanium.UI.setBackgroundColor('#000');

var firstCall = require('TestSingleton');
var NewWin = require('NewWin');

var win1 = Titanium.UI.createWindow({  
    title:'Win 1',
    backgroundColor:'#fff'
});

var label1 = Titanium.UI.createLabel({
	color:'#999',
	text:firstCall.pullString(),
	font:{fontSize:20,fontFamily:'Helvetica Neue'},
	textAlign:'center',
	width:'auto'
});

win1.add(label1);

win1.open(); // open first window

// open second window on click
win1.addEventListener("click",function(){
	firstCall.updateString("singleton value was updated"); // update the private string in the singleton
	win2 = new NewWin();
	win2.open();
});

NewWin.js

var secondCall = require('TestSingleton');

var NewWindow = function() {
	var win = Titanium.UI.createWindow({  
	    title:'Win 2',
	    backgroundColor:'#c00'
	});
	
	var label1 = Titanium.UI.createLabel({
		color:'#999',
		text:secondCall.pullString(),
		font:{fontSize:20,fontFamily:'Helvetica Neue'},
		textAlign:'center',
		width:'auto'
	});
	
	win.add(label1);
	
	return win;
};


module.exports = NewWindow;

TestSingleton.js

var TestSingleton = (function(){
	var private_string = "initial singleton value";
	
	function updateString(str) {
		private_string = str;
	};
	
	function pullString() {
		return private_string;
	};
	
	return {
		updateString:updateString,
		pullString:pullString,
	};
})();

module.exports = TestSingleton;