freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/manipulating-complex-objects.english.md

id, title, challengeType

id	title	challengeType
56533eb9ac21ba0edf2244cb	Manipulating Complex Objects	1

Description

Sometimes you may want to store data in a flexible Data Structure. A JavaScript object is one way to handle flexible data. They allow for arbitrary combinations of strings, numbers, booleans, arrays, functions, and objects. Here's an example of a complex data structure:

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 metadata 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 or JSON is a related data interchange format used to store data.

{
  "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.

Tests

tests:
  - text: <code>myMusic</code> should be an array
    testString: assert(Array.isArray(myMusic), '<code>myMusic</code> should be an array');
  - text: <code>myMusic</code> should have at least two elements
    testString: assert(myMusic.length > 1, '<code>myMusic</code> should have at least two elements');
  - text: <code>myMusic[1]</code> should be an object
    testString: assert(typeof myMusic[1] === 'object', '<code>myMusic[1]</code> should be an object');
  - text: <code>myMusic[1]</code> should have at least 4 properties
    testString: assert(Object.keys(myMusic[1]).length > 3, '<code>myMusic[1]</code> should have at least 4 properties');
  - text: <code>myMusic[1]</code> should contain an <code>artist</code> property which is a string
    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');
  - text: <code>myMusic[1]</code> should  contain a <code>title</code> property which is a string
    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');
  - text: <code>myMusic[1]</code> should contain a <code>release_year</code> property which is a number
    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');
  - text: <code>myMusic[1]</code> should contain a <code>formats</code> property which is an array
    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');
  - text: <code>formats</code> should be an array of strings with at least two elements
    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');

Challenge Seed

var myMusic = [
  {
    "artist": "Billy Joel",
    "title": "Piano Man",
    "release_year": 1973,
    "formats": [
      "CD",
      "8T",
      "LP"
    ],
    "gold": true
  }
  // Add record here
];

After Test

(function(x){ if (Array.isArray(x)) { return JSON.stringify(x); } return "myMusic is not an array"})(myMusic);

Solution

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",
  ]
  }
];