Multi-class in JS

gistfile1.js

function User() {
  this.name = 'Sasha';
}

User.prototype.login = function() {
  console.log("Hello, " + this.name);
};

function Admin(self) {
  if (self) {
    self.admin = this;
  }
  this.title = 'admin';
}

Admin.prototype.moderate = function() {
  console.log("Hello, moderator " + this.title + " " + this.name);
};

var user = new User();
user.login();
user.admin = new Admin(user);
user.admin.moderate();