---
id: 587d7db1367417b2b2512b88
title: Override Inherited Methods
challengeType: 1
---
## Description
In previous lessons, you learned that an object can inherit its behavior (methods) from another object by cloning its prototype object:
ChildObject.prototype = Object.create(ParentObject.prototype);
Then the ChildObject received its own methods by chaining them onto its prototype:
ChildObject.prototype.methodName = function() {...};
It's possible to override an inherited method. It's done the same way - by adding a method to ChildObject.prototype using the same method name as the one to override.
Here's an example of Bird overriding the eat() method inherited from Animal:
function Animal() { }
Animal.prototype.eat = function() {
return "nom nom nom";
};
function Bird() { }
// Inherit all methods from Animal
Bird.prototype = Object.create(Animal.prototype);
// Bird.eat() overrides Animal.eat()
Bird.prototype.eat = function() {
return "peck peck peck";
};
If you have an instance let duck = new Bird(); and you call duck.eat(), this is how JavaScript looks for the method on duck’s prototype chain:
1. duck => Is eat() defined here? No.
2. Bird => Is eat() defined here? => Yes. Execute it and stop searching.
3. Animal => eat() is also defined, but JavaScript stopped searching before reaching this level.
4. Object => JavaScript stopped searching before reaching this level.
## Instructions
Override the fly() method for Penguin so that it returns "Alas, this is a flightless bird."
## Tests
```yml
tests:
- text: penguin.fly() should return the string "Alas, this is a flightless bird."
testString: assert(penguin.fly() === "Alas, this is a flightless bird.", 'penguin.fly() should return the string "Alas, this is a flightless bird."');
- text: The bird.fly() method should return "I am flying!"
testString: assert((new Bird()).fly() === "I am flying!", 'The bird.fly() method should return "I am flying!"');
```
## Challenge Seed
```js
function Bird() { }
Bird.prototype.fly = function() { return "I am flying!"; };
function Penguin() { }
Penguin.prototype = Object.create(Bird.prototype);
Penguin.prototype.constructor = Penguin;
// Add your code below this line
// Add your code above this line
let penguin = new Penguin();
console.log(penguin.fly());
```
## Solution
```js
function Bird() { }
Bird.prototype.fly = function() { return "I am flying!"; };
function Penguin() { }
Penguin.prototype = Object.create(Bird.prototype);
Penguin.prototype.constructor = Penguin;
Penguin.prototype.fly = () => 'Alas, this is a flightless bird.';
let penguin = new Penguin();
console.log(penguin.fly());
```