409c39abf1
* feat(curriculum): Add Basic JS Scrimba links * Fix: Add missing video url. * fix: update videoUrl
121 lines
5.3 KiB
Markdown
121 lines
5.3 KiB
Markdown
---
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id: 56533eb9ac21ba0edf2244cb
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title: Manipulating Complex Objects
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/c9yNMfR'
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---
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## Description
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<section id='description'>
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Sometimes you may want to store data in a flexible <dfn>Data Structure</dfn>. A JavaScript object is one way to handle flexible data. They allow for arbitrary combinations of <dfn>strings</dfn>, <dfn>numbers</dfn>, <dfn>booleans</dfn>, <dfn>arrays</dfn>, <dfn>functions</dfn>, and <dfn>objects</dfn>.
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Here's an example of a complex data structure:
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<blockquote>var ourMusic = [<br> {<br> "artist": "Daft Punk",<br> "title": "Homework",<br> "release_year": 1997,<br> "formats": [ <br> "CD", <br> "Cassette", <br> "LP"<br> ],<br> "gold": true<br> }<br>];</blockquote>
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This is an array which contains one object inside. The object has various pieces of <dfn>metadata</dfn> about an album. It also has a nested <code>"formats"</code> array. If you want to add more album records, you can do this by adding records to the top level array.
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Objects hold data in a property, which has a key-value format. In the example above, <code>"artist": "Daft Punk"</code> is a property that has a key of <code>"artist"</code> and a value of <code>"Daft Punk"</code>.
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<a href='http://www.json.org/' target=_blank>JavaScript Object Notation</a> or <code>JSON</code> is a related data interchange format used to store data.
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<blockquote>{<br> "artist": "Daft Punk",<br> "title": "Homework",<br> "release_year": 1997,<br> "formats": [ <br> "CD",<br> "Cassette",<br> "LP"<br> ],<br> "gold": true<br>}</blockquote>
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<strong>Note</strong><br>You will need to place a comma after every object in the array, unless it is the last object in the array.
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</section>
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## Instructions
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<section id='instructions'>
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Add a new album to the <code>myMusic</code> array. Add <code>artist</code> and <code>title</code> strings, <code>release_year</code> number, and a <code>formats</code> array of strings.
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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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tests:
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- text: <code>myMusic</code> should be an array
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testString: assert(Array.isArray(myMusic), '<code>myMusic</code> should be an array');
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- text: <code>myMusic</code> should have at least two elements
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testString: assert(myMusic.length > 1, '<code>myMusic</code> should have at least two elements');
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- text: <code>myMusic[1]</code> should be an object
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testString: assert(typeof myMusic[1] === 'object', '<code>myMusic[1]</code> should be an object');
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- text: <code>myMusic[1]</code> should have at least 4 properties
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testString: assert(Object.keys(myMusic[1]).length > 3, '<code>myMusic[1]</code> should have at least 4 properties');
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- text: <code>myMusic[1]</code> should contain an <code>artist</code> property which is a string
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testString: assert(myMusic[1].hasOwnProperty('artist') && typeof myMusic[1].artist === 'string', '<code>myMusic[1]</code> should contain an <code>artist</code> property which is a string');
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- text: <code>myMusic[1]</code> should contain a <code>title</code> property which is a string
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testString: assert(myMusic[1].hasOwnProperty('title') && typeof myMusic[1].title === 'string', '<code>myMusic[1]</code> should contain a <code>title</code> property which is a string');
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- text: <code>myMusic[1]</code> should contain a <code>release_year</code> property which is a number
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testString: assert(myMusic[1].hasOwnProperty('release_year') && typeof myMusic[1].release_year === 'number', '<code>myMusic[1]</code> should contain a <code>release_year</code> property which is a number');
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- text: <code>myMusic[1]</code> should contain a <code>formats</code> property which is an array
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testString: assert(myMusic[1].hasOwnProperty('formats') && Array.isArray(myMusic[1].formats), '<code>myMusic[1]</code> should contain a <code>formats</code> property which is an array');
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- text: <code>formats</code> should be an array of strings with at least two elements
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testString: assert(myMusic[1].formats.every(function(item) { return (typeof item === "string")}) && myMusic[1].formats.length > 1, '<code>formats</code> should be an array of strings with at least two elements');
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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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var myMusic = [
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{
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"artist": "Billy Joel",
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"title": "Piano Man",
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"release_year": 1973,
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"formats": [
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"CD",
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"8T",
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"LP"
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],
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"gold": true
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}
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// Add record here
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];
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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(function(x){ if (Array.isArray(x)) { return JSON.stringify(x); } return "myMusic is not an array"})(myMusic);
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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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var myMusic = [
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{
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"artist": "Billy Joel",
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"title": "Piano Man",
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"release_year": 1973,
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"formats": [
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"CS",
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"8T",
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"LP" ],
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"gold": true
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},
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{
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"artist": "ABBA",
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"title": "Ring Ring",
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"release_year": 1973,
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"formats": [
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"CS",
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"8T",
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"LP",
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"CD",
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]
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}
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];
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```
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</section>
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