freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/object-oriented-programming/use-a-constructor-to-create-objects.english.md

id, title, challengeType, forumTopicId

id	title	challengeType	forumTopicId
587d7dad367417b2b2512b78	Use a Constructor to Create Objects	1	18233

Description

Here's the Bird constructor from the previous challenge:

function Bird() {
  this.name = "Albert";
  this.color  = "blue";
  this.numLegs = 2;
  // "this" inside the constructor always refers to the object being created
}

let blueBird = new Bird();

Notice that the new operator is used when calling a constructor. This tells JavaScript to create a new instance of Bird called blueBird. Without the new operator, this inside the constructor would not point to the newly created object, giving unexpected results. Now blueBird has all the properties defined inside the Bird constructor:

blueBird.name; // => Albert
blueBird.color; // => blue
blueBird.numLegs; // => 2

Just like any other object, its properties can be accessed and modified:

blueBird.name = 'Elvira';
blueBird.name; // => Elvira

Instructions

Use the Dog constructor from the last lesson to create a new instance of Dog, assigning it to a variable hound.

Tests

tests:
  - text: <code>hound</code> should be created using the <code>Dog</code> constructor.
    testString: assert(hound instanceof Dog);
  - text: Your code should use the <code>new</code> operator to create an instance of <code>Dog</code>.
    testString: assert(code.match(/new/g));

Challenge Seed

function Dog() {
  this.name = "Rupert";
  this.color = "brown";
  this.numLegs = 4;
}
// Only change code below this line

Solution

function Dog() {
  this.name = "Rupert";
  this.color = "brown";
  this.numLegs = 4;
}
const hound = new Dog();