72 lines
2.0 KiB
Markdown
72 lines
2.0 KiB
Markdown
|
---
|
||
|
|
id: 587d7dad367417b2b2512b75
|
||
|
|
title: Create a Method on an Object
|
||
|
|
challengeType: 1
|
||
|
|
---
|
||
|
|
|
||
|
|
## Description
|
||
|
|
<section id='description'>
|
||
|
|
<code>Objects</code> can have a special type of <code>property</code>, called a <code>method</code>.
|
||
|
|
<code>Methods</code> are <code>properties</code> that are functions. This adds different behavior to an <code>object</code>. Here is the <code>duck</code> example with a method:
|
||
|
|
<blockquote>let duck = {<br> name: "Aflac",<br> numLegs: 2,<br> sayName: function() {return "The name of this duck is " + duck.name + ".";}<br>};<br>duck.sayName();<br>// Returns "The name of this duck is Aflac."</blockquote>
|
||
|
|
The example adds the <code>sayName</code> <code>method</code>, which is a function that returns a sentence giving the name of the <code>duck</code>.
|
||
|
|
Notice that the <code>method</code> accessed the <code>name</code> property in the return statement using <code>duck.name</code>. The next challenge will cover another way to do this.
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Instructions
|
||
|
|
<section id='instructions'>
|
||
|
|
Using the <code>dog</code> <code>object</code>, give it a method called <code>sayLegs</code>. The method should return the sentence "This dog has 4 legs."
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Tests
|
||
|
|
<section id='tests'>
|
||
|
|
|
||
|
|
```yml
|
||
|
|
- text: <code>dog.sayLegs()</code> should be a function.
|
||
|
|
testString: 'assert(typeof(dog.sayLegs) === "function", "<code>dog.sayLegs()</code> should be a function.");'
|
||
|
|
- text: <code>dog.sayLegs()</code> should return the given string - note that punctuation and spacing matter.
|
||
|
|
testString: 'assert(dog.sayLegs() === "This dog has 4 legs.", "<code>dog.sayLegs()</code> should return the given string - note that punctuation and spacing matter.");'
|
||
|
|
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Challenge Seed
|
||
|
|
<section id='challengeSeed'>
|
||
|
|
|
||
|
|
<div id='js-seed'>
|
||
|
|
|
||
|
|
```js
|
||
|
|
let dog = {
|
||
|
|
name: "Spot",
|
||
|
|
numLegs: 4,
|
||
|
|
|
||
|
|
};
|
||
|
|
|
||
|
|
dog.sayLegs();
|
||
|
|
```
|
||
|
|
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</section>
|
||
|
|
|
||
|
|
## Solution
|
||
|
|
<section id='solution'>
|
||
|
|
|
||
|
|
|
||
|
|
```js
|
||
|
|
let dog = {
|
||
|
|
name: "Spot",
|
||
|
|
numLegs: 4,
|
||
|
|
sayLegs () {
|
||
|
|
return 'This dog has ' + this.numLegs + ' legs.';
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
dog.sayLegs();
|
||
|
|
```
|
||
|
|
|
||
|
|
</section>
|