pseudoclassical.js

var Phone = function(phoneNumber) {
  this.phoneNumber = phoneNumber;
};

Phone.prototype = {
  send: function(recipientPhoneNumber, message) {
    console.log('sending the text message "'+ message +'" to ' + recipientPhoneNumber)
  }
};

var SmartPhone = function(phoneNumber, phoneEmail) {
  this.phoneNumber = phoneNumber;
  this.phoneEmail = phoneEmail;
};

SmartPhone.prototype.oldSend = Phone.prototype.send;

SmartPhone.prototype.send = function(recipientPhoneNumberOrEmail, message) {
  if(typeof recipientPhoneNumberOrEmail === 'number'){
    var recipientPhoneNumber = recipientPhoneNumberOrEmail;
    this.oldSend(recipientPhoneNumber, message);
  }
  else {
    var recipientEmail = recipientPhoneNumberOrEmail;
    console.log('sending the email message "'+ message +'" to ' + recipientEmail);
  };
}