65 lines
2.5 KiB
Markdown
65 lines
2.5 KiB
Markdown
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---
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id: 587d7dad367417b2b2512b77
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title: 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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<code>Constructors</code> are functions that create new objects. They define properties and behaviors that will belong to the new object. Think of them as a blueprint for the creation of new objects.
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Here is an example of a <code>constructor</code>:
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<blockquote>function Bird() {<br> this.name = "Albert";<br> this.color = "blue";<br> this.numLegs = 2;<br>}</blockquote>
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This <code>constructor</code> defines a <code>Bird</code> object with properties <code>name</code>, <code>color</code>, and <code>numLegs</code> set to Albert, blue, and 2, respectively.
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<code>Constructors</code> follow a few conventions:
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<ul><li><code>Constructors</code> are defined with a capitalized name to distinguish them from other functions that are not <code>constructors</code>.</li><li><code>Constructors</code> use the keyword <code>this</code> to set properties of the object they will create. Inside the <code>constructor</code>, <code>this</code> refers to the new object it will create.</li><li><code>Constructors</code> define properties and behaviors instead of returning a value as other functions might.</li></ul>
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</section>
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## Instructions
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<section id='instructions'>
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Create a <code>constructor</code>, <code>Dog</code>, with properties <code>name</code>, <code>color</code>, and <code>numLegs</code> that are set to a string, a string, and a number, respectively.
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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>Dog</code> should have a <code>name</code> property set to a string.
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testString: 'assert(typeof (new Dog()).name === "string", "<code>Dog</code> should have a <code>name</code> property set to a string.");'
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- text: <code>Dog</code> should have a <code>color</code> property set to a string.
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testString: 'assert(typeof (new Dog()).color === "string", "<code>Dog</code> should have a <code>color</code> property set to a string.");'
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- text: <code>Dog</code> should have a <code>numLegs</code> property set to a number.
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testString: 'assert(typeof (new Dog()).numLegs === "number", "<code>Dog</code> should have a <code>numLegs</code> property set to a number.");'
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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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```
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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 Dog (name, color, numLegs) {
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this.name = 'name';
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this.color = 'color';
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this.numLegs = 4;
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}
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```
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</section>
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