问我可以在Javascript中“扩展”闭包定义的“类”吗？

EN

var Welcomer = function(name) {
  var pName = name;
  var pMessage = function() {
    return "Hi, " + pName + "!";
  };

  return {
    sayHi: function() {
      alert(pMessage());
    }
  };
};

new Welcomer('Sue').sayHi();

var UnhappyWelcomer = function(name) {
  var pSadMessage = function() {
    // won't work, b/c I don't have access to pMessage
    return pMessage() + " Miserable day, innit?";
  };

  return {
    sayHi: function() {
      alert(pSadMessage());
    }
  };
};
UnhappyWelcomer.prototype = Welcomer(); // failed attempt at inheritance

new UnhappyWelcomer().sayHi();