2018-09-30 23:01:58 +01:00
---
id: 587d7b8b367417b2b2512b53
title: Use class Syntax to Define a Constructor Function
challengeType: 1
2019-08-05 09:17:33 -07:00
forumTopicId: 301212
2018-09-30 23:01:58 +01:00
---
## Description
<section id='description'>
2019-11-24 21:38:30 +00:00
ES6 provides a new syntax to create objects, using the <dfn>class</dfn> keyword.
It should be noted that the <code>class</code> syntax is just syntax, and not a full-fledged class-based implementation of an object-oriented paradigm, unlike in languages such as Java, Python, Ruby, etc.
In ES5, we usually define a constructor function and use the <code>new</code> keyword to instantiate an object.
2019-05-17 06:20:30 -07:00
```js
var SpaceShuttle = function(targetPlanet){
this.targetPlanet = targetPlanet;
}
var zeus = new SpaceShuttle('Jupiter');
```
2019-11-24 21:38:30 +00:00
The <code>class</code> syntax simply replaces the constructor function creation:
2019-05-17 06:20:30 -07:00
```js
class SpaceShuttle {
constructor(targetPlanet) {
this.targetPlanet = targetPlanet;
}
}
const zeus = new SpaceShuttle('Jupiter');
```
2019-11-24 21:38:30 +00:00
It should be noted that the <code>class</code> keyword declares a new function, to which a constructor is added. This constructor is invoked when <code>new</code> is called to create a new object.<br>
2019-03-26 12:53:19 -04:00
<strong>Notes:</strong><br><ul>
<li> UpperCamelCase should be used by convention for ES6 class names, as in <code>SpaceShuttle</code> used above.</li>
2019-03-28 09:35:41 +01:00
<li> The constructor method is a special method for creating and initializing an object created with a class. You will learn more about it in the Object Oriented Programming section of the JavaScript Algorithms And Data Structures Certification.</li></ul>
2018-09-30 23:01:58 +01:00
</section>
## Instructions
<section id='instructions'>
2019-11-24 21:38:30 +00:00
Use the <code>class</code> keyword and write a constructor to create the <code>Vegetable</code> class.
The <code>Vegetable</code> class allows you to create a vegetable object with a property <code>name</code> that gets passed to the constructor.
2018-09-30 23:01:58 +01:00
</section>
## Tests
<section id='tests'>
```yml
2018-10-04 14:37:37 +01:00
tests:
- text: <code>Vegetable</code> should be a <code>class</code> with a defined <code>constructor</code> method.
2019-03-25 19:49:34 +05:30
testString: assert(typeof Vegetable === 'function' && typeof Vegetable.constructor === 'function');
- text: <code>class</code> keyword should be used.
testString: assert(code.match(/class/g));
- text: <code>Vegetable</code> should be able to be instantiated.
testString: assert(() => {const a = new Vegetable("apple"); return typeof a === 'object';});
2018-10-04 14:37:37 +01:00
- text: <code>carrot.name</code> should return <code>carrot</code>.
2019-03-25 19:49:34 +05:30
testString: assert(carrot.name=='carrot');
2018-09-30 23:01:58 +01:00
```
</section>
## Challenge Seed
<section id='challengeSeed'>
<div id='js-seed'>
```js
2020-03-04 13:08:54 -06:00
// Only change code below this line
2019-03-25 19:49:34 +05:30
2020-03-04 13:08:54 -06:00
// Only change code above this line
2018-09-30 23:01:58 +01:00
const carrot = new Vegetable('carrot');
2020-03-04 13:08:54 -06:00
console.log(carrot.name); // Should display 'carrot'
2018-09-30 23:01:58 +01:00
```
</div>
</section>
## Solution
<section id='solution'>
```js
2019-03-25 19:49:34 +05:30
class Vegetable {
constructor(name) {
this.name = name;
2019-01-24 20:36:57 +00:00
}
}
const carrot = new Vegetable('carrot');
2018-09-30 23:01:58 +01:00
```
2019-07-18 08:24:12 -07:00
2018-09-30 23:01:58 +01:00
</section>