function Person(name) {
  this.name = name || "public";
  // 1. privileged
  this.getName = function() {
    return this.name + ', ' + privateMethod();
  }
  // 2. private
  var privates = 'private';
  function privateMethod() {
    return privates;
  }
}

// Public methods
Person.prototype = {
	getDate: function() {
		return new Date();
	},
	getWorld: function(){
		return this.name;
	}
}

// Public Static method:
Person.act = function() {
  return Person.constructor.prototype.constructor;
}

var p = new Person();
p.getName('william Jiang');
p.getDate();
p.getWorld();
Person.act();