JavaScript Singleton

JavaScript Singleton

// http://prototyp.ical.ly/index.php/2007/03/01/javascript-design-patterns-1-the-singleton/
// http://books.google.co.uk/books?id=za3vlnlWxb0C&printsec=frontcover&source=gbs_navlinks_s#v=onepage&q=singleton&f=false

var mySingleton = function()
{
  /* private attributes */
  var _created = new Date();
  /* private methods */
  var _calculateAge = function()
  {
    return new Date().getTime() - _created.getTime();
  }
  return {
    /* public attributes*/
    name: 'M.Y. Singleton',
    /* public methods */
    tellBirthday:function()
    {
      alert('Hello, my name is ' + this.name + ' and I was created on ' + _created.toLocaleString()  +');
    },
    tellAge:function()
    {
      alert('I am '+_calculateAge()+'ms old.');
    }
  }
}();