​

// Plain JS, works as expected

// ###########################

var Animal = function() {

  var self = this;

  self.hello = function() {

     return 'Not implemented';

  };

  self.greeting = function() {

    return self.hello() + '!!';

  };

};

​

var dog = new Animal();

dog.hello = function() {

  return 'Woff';

};

console.log(dog.greeting());

​

​

// Knockout

// ########

var KOAnimal = function() {

  var self = this;

  self.hello = ko.computed(function() {

    return 'KO Not implemented';

  });

  self.greeting = ko.computed(function() {

    return self.hello() + '!!';

  });

};

​

var kodog = new KOAnimal();

kodog.hello = ko.computed(function() {

  return 'KOWooff';

});

console.log(kodog.greeting());

​