72 lines
2.8 KiB
Markdown
72 lines
2.8 KiB
Markdown
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---
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id: 587d7b8b367417b2b2512b53
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title: Use class Syntax to Define a Constructor Function
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challengeType: 1
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---
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## Description
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<section id='description'>
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ES6 provides a new syntax to help create objects, using the keyword <dfn>class</dfn>.
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This is to be noted, that the <code>class</code> syntax is just a syntax, and not a full-fledged class based implementation of object oriented paradigm, unlike in languages like Java, or Python, or Ruby etc.
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In ES5, we usually define a constructor function, and use the <code>new</code> keyword to instantiate an object.
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<blockquote>var SpaceShuttle = function(targetPlanet){<br> this.targetPlanet = targetPlanet;<br>}<br>var zeus = new SpaceShuttle('Jupiter');</blockquote>
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The class syntax simply replaces the constructor function creation:
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<blockquote>class SpaceShuttle {<br> constructor(targetPlanet){<br> this.targetPlanet = targetPlanet;<br> }<br>}<br>const zeus = new SpaceShuttle('Jupiter');</blockquote>
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Notice that the <code>class</code> keyword declares a new function, and a constructor was added, which would be invoked when <code>new</code> is called - to create a new object.
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</section>
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## Instructions
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<section id='instructions'>
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Use <code>class</code> keyword and write a proper constructor to create the <code>Vegetable</code> class.
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The <code>Vegetable</code> lets you create a vegetable object, with a property <code>name</code>, to be passed to constructor.
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</section>
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## Tests
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<section id='tests'>
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```yml
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- text: <code>Vegetable</code> should be a <code>class</code> with a defined <code>constructor</code> method.
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testString: 'assert(typeof Vegetable === "function" && typeof Vegetable.constructor === "function", "<code>Vegetable</code> should be a <code>class</code> with a defined <code>constructor</code> method.");'
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- text: <code>class</code> keyword was used.
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testString: 'getUserInput => assert(getUserInput("index").match(/class/g),"<code>class</code> keyword was used.");'
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- text: <code>Vegetable</code> can be instantiated.
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testString: 'assert(() => {const a = new Vegetable("apple"); return typeof a === "object";},"<code>Vegetable</code> can be instantiated.");'
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- text: <code>carrot.name</code> should return <code>carrot</code>.
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testString: 'assert(carrot.name=="carrot","<code>carrot.name</code> should return <code>carrot</code>.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function makeClass() {
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"use strict";
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/* Alter code below this line */
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/* Alter code above this line */
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return Vegetable;
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}
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const Vegetable = makeClass();
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const carrot = new Vegetable('carrot');
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console.log(carrot.name); // => should be 'carrot'
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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