178 lines
3.7 KiB
Markdown
178 lines
3.7 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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forumTopicId: 18208
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dashedName: manipulating-complex-objects
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---
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# --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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```js
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var ourMusic = [
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{
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"artist": "Daft Punk",
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"title": "Homework",
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"release_year": 1997,
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"formats": [
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"CD",
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"Cassette",
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"LP"
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],
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"gold": true
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}
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];
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```
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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 `"formats"` array. If you want to add more album records, you can do this by adding records to the top level array. Objects hold data in a property, which has a key-value format. In the example above, `"artist": "Daft Punk"` is a property that has a key of `"artist"` and a value of `"Daft Punk"`. [JavaScript Object Notation](http://www.json.org/) or `JSON` is a related data interchange format used to store data.
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```json
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{
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"artist": "Daft Punk",
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"title": "Homework",
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"release_year": 1997,
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"formats": [
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"CD",
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"Cassette",
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"LP"
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],
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"gold": true
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}
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```
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**Note**
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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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# --instructions--
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Add a new album to the `myMusic` array. Add `artist` and `title` strings, `release_year` number, and a `formats` array of strings.
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# --hints--
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`myMusic` should be an array
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```js
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assert(Array.isArray(myMusic));
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```
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`myMusic` should have at least two elements
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```js
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assert(myMusic.length > 1);
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```
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`myMusic[1]` should be an object
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```js
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assert(typeof myMusic[1] === 'object');
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```
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`myMusic[1]` should have at least 4 properties
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```js
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assert(Object.keys(myMusic[1]).length > 3);
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```
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`myMusic[1]` should contain an `artist` property which is a string
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```js
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assert(
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myMusic[1].hasOwnProperty('artist') && typeof myMusic[1].artist === 'string'
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);
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```
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`myMusic[1]` should contain a `title` property which is a string
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```js
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assert(
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myMusic[1].hasOwnProperty('title') && typeof myMusic[1].title === 'string'
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);
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```
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`myMusic[1]` should contain a `release_year` property which is a number
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```js
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assert(
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myMusic[1].hasOwnProperty('release_year') &&
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typeof myMusic[1].release_year === 'number'
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);
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```
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`myMusic[1]` should contain a `formats` property which is an array
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```js
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assert(
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myMusic[1].hasOwnProperty('formats') && Array.isArray(myMusic[1].formats)
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);
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```
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`formats` should be an array of strings with at least two elements
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```js
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assert(
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myMusic[1].formats.every(function (item) {
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return typeof item === 'string';
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}) && myMusic[1].formats.length > 1
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);
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```
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# --seed--
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## --after-user-code--
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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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## --seed-contents--
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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 a record here
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];
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```
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# --solutions--
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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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