How to retrive password value with four digits

app.js

var win = Ti.UI.createWindow({

backgroundColor : 'orange',

layout:'vertical'

});

var textField = Ti.UI.createTextField({
	  borderStyle: Ti.UI.INPUT_BORDERSTYLE_ROUNDED,
	  color: '#336699',
	  top: 10, left: 10,
	  maxLength:4,
	  width: 250, height: 60,
	  passwordMask:true
	});
	win.add(textField);
	
	
	var button = Titanium.UI.createButton({
		   title: 'Sent',
		   top: 100,
		   width: 100,
		   height: 50
		});
		button.addEventListener('click',function(e)
		{
		   alert(textField.value);
		});
		
		win.add(button);		

win.open();