101 lines
2.5 KiB
Markdown
101 lines
2.5 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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forumTopicId: 301212
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dashedName: use-class-syntax-to-define-a-constructor-function
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---
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# --description--
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ES6 provides a new syntax to create objects, using the <dfn>class</dfn> keyword.
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It should be noted that the `class` 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.
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In ES5, we usually define a `constructor` function and use the `new` keyword to instantiate an object.
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```js
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var SpaceShuttle = function(targetPlanet){
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this.targetPlanet = targetPlanet;
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}
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var zeus = new SpaceShuttle('Jupiter');
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```
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The `class` syntax simply replaces the `constructor` function creation:
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```js
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class SpaceShuttle {
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constructor(targetPlanet) {
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this.targetPlanet = targetPlanet;
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}
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}
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const zeus = new SpaceShuttle('Jupiter');
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```
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It should be noted that the `class` keyword declares a new function, to which a constructor is added. This constructor is invoked when `new` is called to create a new object.
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**Note:** UpperCamelCase should be used by convention for ES6 class names, as in `SpaceShuttle` used above.
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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.
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# --instructions--
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Use the `class` keyword and write a `constructor` to create the `Vegetable` class.
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The `Vegetable` class allows you to create a vegetable object with a property `name` that gets passed to the `constructor`.
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# --hints--
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`Vegetable` should be a `class` with a defined `constructor` method.
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```js
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assert(
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typeof Vegetable === 'function' && typeof Vegetable.constructor === 'function'
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);
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```
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The `class` keyword should be used.
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```js
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assert(code.match(/class/g));
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```
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`Vegetable` should be able to be instantiated.
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```js
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assert(() => {
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const a = new Vegetable('apple');
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return typeof a === 'object';
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});
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```
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`carrot.name` should return `carrot`.
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```js
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assert(carrot.name == 'carrot');
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```
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# --seed--
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## --seed-contents--
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```js
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// Only change code below this line
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// Only change code above this line
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const carrot = new Vegetable('carrot');
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console.log(carrot.name); // Should display 'carrot'
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```
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# --solutions--
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```js
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class Vegetable {
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constructor(name) {
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this.name = name;
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}
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}
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const carrot = new Vegetable('carrot');
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```
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