180 lines
3.9 KiB
Markdown
180 lines
3.9 KiB
Markdown
---
|
|
id: 56533eb9ac21ba0edf2244cb
|
|
title: Manipulating Complex Objects
|
|
challengeType: 1
|
|
videoUrl: 'https://scrimba.com/c/c9yNMfR'
|
|
forumTopicId: 18208
|
|
dashedName: manipulating-complex-objects
|
|
---
|
|
|
|
# --description--
|
|
|
|
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>.
|
|
|
|
Here's an example of a complex data structure:
|
|
|
|
```js
|
|
var ourMusic = [
|
|
{
|
|
"artist": "Daft Punk",
|
|
"title": "Homework",
|
|
"release_year": 1997,
|
|
"formats": [
|
|
"CD",
|
|
"Cassette",
|
|
"LP"
|
|
],
|
|
"gold": true
|
|
}
|
|
];
|
|
```
|
|
|
|
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.
|
|
|
|
```json
|
|
{
|
|
"artist": "Daft Punk",
|
|
"title": "Homework",
|
|
"release_year": 1997,
|
|
"formats": [
|
|
"CD",
|
|
"Cassette",
|
|
"LP"
|
|
],
|
|
"gold": true
|
|
}
|
|
```
|
|
|
|
**Note:** You will need to place a comma after every object in the array, unless it is the last object in the array.
|
|
|
|
# --instructions--
|
|
|
|
Add a new album to the `myMusic` array. Add `artist` and `title` strings, `release_year` number, and a `formats` array of strings.
|
|
|
|
# --hints--
|
|
|
|
`myMusic` should be an array
|
|
|
|
```js
|
|
assert(Array.isArray(myMusic));
|
|
```
|
|
|
|
`myMusic` should have at least two elements
|
|
|
|
```js
|
|
assert(myMusic.length > 1);
|
|
```
|
|
|
|
The elements in the `myMusic` array should be objects
|
|
|
|
```js
|
|
myMusic.forEach(object => {assert.typeOf(object, 'object')})
|
|
```
|
|
|
|
Your object in `myMusic` should have at least 4 properties
|
|
|
|
```js
|
|
myMusic.forEach(object => {assert(Object.keys(object).length > 3); });
|
|
```
|
|
|
|
Your object in `myMusic` should contain the property `artist` which is a string
|
|
|
|
```js
|
|
myMusic.forEach(object => {
|
|
assert.containsAllKeys(object, ['artist']);
|
|
assert.typeOf(object.artist, 'string')
|
|
})
|
|
```
|
|
|
|
Your object in `myMusic` should contain the property `title` which is a string
|
|
|
|
```js
|
|
myMusic.forEach(object => {
|
|
assert.containsAllKeys(object, ['title']);
|
|
assert.typeOf(object.title, 'string')
|
|
})
|
|
```
|
|
|
|
Your object in `myMusic` should contain the property `release_year` which is a number
|
|
|
|
```js
|
|
myMusic.forEach(object => {
|
|
assert.containsAllKeys(object, ['release_year']);
|
|
assert.typeOf(object.release_year, 'number')
|
|
})
|
|
```
|
|
|
|
Your object in `myMusic` should contain a `formats` property which is an array
|
|
|
|
```js
|
|
myMusic.forEach(object => {
|
|
assert.containsAllKeys(object, ['formats']);
|
|
assert.typeOf(object.formats, 'array')
|
|
})
|
|
```
|
|
|
|
`formats` should be an array of strings with at least two elements
|
|
|
|
```js
|
|
myMusic.forEach(object => {
|
|
object.formats.forEach(format => {
|
|
assert.typeOf(format, 'string')
|
|
});
|
|
assert.isAtLeast(object.formats.length, 2)
|
|
})
|
|
```
|
|
|
|
# --seed--
|
|
|
|
## --after-user-code--
|
|
|
|
```js
|
|
(function(x){ if (Array.isArray(x)) { return JSON.stringify(x); } return "myMusic is not an array"})(myMusic);
|
|
```
|
|
|
|
## --seed-contents--
|
|
|
|
```js
|
|
var myMusic = [
|
|
{
|
|
"artist": "Billy Joel",
|
|
"title": "Piano Man",
|
|
"release_year": 1973,
|
|
"formats": [
|
|
"CD",
|
|
"8T",
|
|
"LP"
|
|
],
|
|
"gold": true
|
|
}
|
|
];
|
|
```
|
|
|
|
# --solutions--
|
|
|
|
```js
|
|
var myMusic = [
|
|
{
|
|
"artist": "Billy Joel",
|
|
"title": "Piano Man",
|
|
"release_year": 1973,
|
|
"formats": [
|
|
"CS",
|
|
"8T",
|
|
"LP" ],
|
|
"gold": true
|
|
},
|
|
{
|
|
"artist": "ABBA",
|
|
"title": "Ring Ring",
|
|
"release_year": 1973,
|
|
"formats": [
|
|
"CS",
|
|
"8T",
|
|
"LP",
|
|
"CD",
|
|
]
|
|
}
|
|
];
|
|
```
|