82 lines
2.5 KiB
Markdown
82 lines
2.5 KiB
Markdown
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---
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id: 587d7db1367417b2b2512b86
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title: Reset an Inherited Constructor Property
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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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When an object inherits its <code>prototype</code> from another object, it also inherits the <code>supertype</code>'s constructor property.
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Here's an example:
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<blockquote>function Bird() { }<br>Bird.prototype = Object.create(Animal.prototype);<br>let duck = new Bird();<br>duck.constructor // function Animal(){...}</blockquote>
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But <code>duck</code> and all instances of <code>Bird</code> should show that they were constructed by <code>Bird</code> and not <code>Animal</code>. To do so, you can manually set <code>Bird's</code> constructor property to the <code>Bird</code> object:
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<blockquote>Bird.prototype.constructor = Bird;<br>duck.constructor // function Bird(){...}</blockquote>
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</section>
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## Instructions
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<section id='instructions'>
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Fix the code so <code>duck.constructor</code> and <code>beagle.constructor</code> return their respective constructors.
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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>Bird.prototype</code> should be an instance of <code>Animal</code>.
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testString: 'assert(Animal.prototype.isPrototypeOf(Bird.prototype), "<code>Bird.prototype</code> should be an instance of <code>Animal</code>.");'
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- text: <code>duck.constructor</code> should return <code>Bird</code>.
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testString: 'assert(duck.constructor === Bird, "<code>duck.constructor</code> should return <code>Bird</code>.");'
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- text: <code>Dog.prototype</code> should be an instance of <code>Animal</code>.
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testString: 'assert(Animal.prototype.isPrototypeOf(Dog.prototype), "<code>Dog.prototype</code> should be an instance of <code>Animal</code>.");'
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- text: <code>beagle.constructor</code> should return <code>Dog</code>.
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testString: 'assert(beagle.constructor === Dog, "<code>beagle.constructor</code> should return <code>Dog</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 Animal() { }
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function Bird() { }
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function Dog() { }
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Bird.prototype = Object.create(Animal.prototype);
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Dog.prototype = Object.create(Animal.prototype);
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// Add your code below this line
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let duck = new Bird();
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let beagle = new Dog();
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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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function Animal() { }
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function Bird() { }
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function Dog() { }
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Bird.prototype = Object.create(Animal.prototype);
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Dog.prototype = Object.create(Animal.prototype);
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Dog.prototype.constructor = Dog;
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Bird.prototype.constructor = Bird;
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let duck = new Bird();
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let beagle = new Dog();
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```
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</section>
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