freeCodeCamp/reset-an-inherited-constructor-property.english.md at e3b0a88910bc38ce87c7c01d0c47e5ab977a79a4

Files

Randell Dawson 05f73ca409 fix(curriculum): Convert blockquote elements to triple backtick syntax for JavaScript Algorithms and Data Structures (#35992 )

* fix: convert js algorithms and data structures

* fix: revert some blocks back to blockquote

* fix: reverted comparison code block to blockquotes

* fix: change js to json

Co-Authored-By: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>

* fix: convert various section to triple backticks

* fix: Make the formatting consistent for comparisons

2019-05-17 08:20:30 -05:00

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id, title, challengeType

id	title	challengeType
587d7db1367417b2b2512b86	Reset an Inherited Constructor Property	1

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

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();

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