1.8 KiB
id, title, challengeType, forumTopicId, dashedName
| id | title | challengeType | forumTopicId | dashedName |
|---|---|---|---|---|
| 587d7dae367417b2b2512b7a | Verify an Object's Constructor with instanceof | 1 | 301337 | verify-an-objects-constructor-with-instanceof |
--description--
Anytime a constructor function creates a new object, that object is said to be an instance of its constructor. JavaScript gives a convenient way to verify this with the instanceof operator. instanceof allows you to compare an object to a constructor, returning true or false based on whether or not that object was created with the constructor. Here's an example:
let Bird = function(name, color) {
this.name = name;
this.color = color;
this.numLegs = 2;
}
let crow = new Bird("Alexis", "black");
crow instanceof Bird; // => true
If an object is created without using a constructor, instanceof will verify that it is not an instance of that constructor:
let canary = {
name: "Mildred",
color: "Yellow",
numLegs: 2
};
canary instanceof Bird; // => false
--instructions--
Create a new instance of the House constructor, calling it myHouse and passing a number of bedrooms. Then, use instanceof to verify that it is an instance of House.
--hints--
myHouse should have a numBedrooms attribute set to a number.
assert(typeof myHouse.numBedrooms === 'number');
You should verify that myHouse is an instance of House using the instanceof operator.
assert(/myHouse\s*instanceof\s*House/.test(code));
--seed--
--seed-contents--
function House(numBedrooms) {
this.numBedrooms = numBedrooms;
}
// Only change code below this line
--solutions--
function House(numBedrooms) {
this.numBedrooms = numBedrooms;
}
const myHouse = new House(4);
console.log(myHouse instanceof House);