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id	title	challengeType	forumTopicId
587d7db1367417b2b2512b86	Reset an Inherited Constructor Property	1	301324

Description

When an object inherits its prototype from another object, it also inherits the supertype's constructor property. Here's an example:

function Bird() { }
Bird.prototype = Object.create(Animal.prototype);
let duck = new Bird();
duck.constructor // function Animal(){...}

But duck and all instances of Bird should show that they were constructed by Bird and not Animal. To do so, you can manually set Bird's constructor property to the Bird object:

Bird.prototype.constructor = Bird;
duck.constructor // function Bird(){...}

Instructions

Fix the code so duck.constructor and beagle.constructor return their respective constructors.

Tests

tests:
  - text: <code>Bird.prototype</code> should be an instance of <code>Animal</code>.
    testString: assert(Animal.prototype.isPrototypeOf(Bird.prototype));
  - text: <code>duck.constructor</code> should return <code>Bird</code>.
    testString: assert(duck.constructor === Bird);
  - text: <code>Dog.prototype</code> should be an instance of <code>Animal</code>.
    testString: assert(Animal.prototype.isPrototypeOf(Dog.prototype));
  - text: <code>beagle.constructor</code> should return <code>Dog</code>.
    testString: assert(beagle.constructor === Dog);

Challenge Seed

function Animal() { }
function Bird() { }
function Dog() { }

Bird.prototype = Object.create(Animal.prototype);
Dog.prototype = Object.create(Animal.prototype);

// Add your code below this line



let duck = new Bird();
let beagle = new Dog();

Solution

function Animal() { }
function Bird() { }
function Dog() { }
Bird.prototype = Object.create(Animal.prototype);
Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;
Bird.prototype.constructor = Bird;
let duck = new Bird();
let beagle = new Dog();

2.3 KiB Raw Blame History