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--description--

You are creating a function that aids in the maintenance of a musical album collection. The collection is organized as an object that contains multiple albums which are also objects. Each album is represented in the collection with a unique id as the property name. Within each album object, there are various properties describing information about the album. Not all albums have complete information.

The updateRecords function takes 4 arguments represented by the following function parameters:

  • records - an object containing several individual albums
  • id - a number representing a specific album in the records object
  • prop - a string representing the name of the album’s property to update
  • value - a string containing the information used to update the album’s property

Complete the function using the rules below to modify the object passed to the function.

  • Your function must always return the entire records object.
  • If value is an empty string, delete the given prop property from the album.
  • If prop isn't tracks and value isn't an empty string, assign the value to that album's prop.
  • If prop is tracks and value isn't an empty string, but the album doesn't have a tracks property, create an empty array and add value to it.
  • If prop is tracks and value isn't an empty string, add value to the end of the album's existing tracks array.

Note: A copy of the recordCollection object is used for the tests. You should not directly modify the recordCollection object.

--hints--

After updateRecords(recordCollection, 5439, "artist", "ABBA"), artist should be the string ABBA

assert(
  updateRecords(_recordCollection, 5439, 'artist', 'ABBA')[5439]['artist'] ===
    'ABBA'
);

After updateRecords(recordCollection, 5439, "tracks", "Take a Chance on Me"), tracks should have the string Take a Chance on Me as the last and only element.

assert(
  updateRecords(_recordCollection, 5439, 'tracks', 'Take a Chance on Me') &&
  _recordCollection[5439]['tracks'].length === 1 &&
  _recordCollection[5439]['tracks'].pop() === 'Take a Chance on Me'
);

After updateRecords(recordCollection, 2548, "artist", ""), artist should not be set

updateRecords(_recordCollection, 2548, 'artist', '');
assert(!_recordCollection[2548].hasOwnProperty('artist'));

After updateRecords(recordCollection, 1245, "tracks", "Addicted to Love"), tracks should have the string Addicted to Love as the last element.

assert(
  updateRecords(_recordCollection, 1245, 'tracks', 'Addicted to Love')[1245][
    'tracks'
  ].pop() === 'Addicted to Love'
);

After updateRecords(recordCollection, 2468, "tracks", "Free"), tracks should have the string 1999 as the first element.

assert(
  updateRecords(_recordCollection, 2468, 'tracks', 'Free')[2468][
    'tracks'
  ][0] === '1999'
);

After updateRecords(recordCollection, 2548, "tracks", ""), tracks should not be set

updateRecords(_recordCollection, 2548, 'tracks', '');
assert(!_recordCollection[2548].hasOwnProperty('tracks'));

After updateRecords(recordCollection, 1245, "albumTitle", "Riptide"), albumTitle should be the string Riptide

assert(
  updateRecords(_recordCollection, 1245, 'albumTitle', 'Riptide')[1245][
    'albumTitle'
  ] === 'Riptide'
);

--seed--

--before-user-code--​

const _recordCollection = {
  2548: {
    albumTitle: 'Slippery When Wet',
    artist: 'Bon Jovi',
    tracks: ['Let It Rock', 'You Give Love a Bad Name']
  },
  2468: {
    albumTitle: '1999',
    artist: 'Prince',
    tracks: ['1999', 'Little Red Corvette']
  },
  1245: {
    artist: 'Robert Palmer',
    tracks: []
  },
  5439: {
    albumTitle: 'ABBA Gold'
  }
};

--seed-contents--​

// Setup
const recordCollection = {
  2548: {
    albumTitle: 'Slippery When Wet',
    artist: 'Bon Jovi',
    tracks: ['Let It Rock', 'You Give Love a Bad Name']
  },
  2468: {
    albumTitle: '1999',
    artist: 'Prince',
    tracks: ['1999', 'Little Red Corvette']
  },
  1245: {
    artist: 'Robert Palmer',
    tracks: []
  },
  5439: {
    albumTitle: 'ABBA Gold'
  }
};

// Only change code below this line
function updateRecords(records, id, prop, value) {
  return records;
}

updateRecords(recordCollection, 5439, 'artist', 'ABBA');

--solutions--

const recordCollection = {
  2548: {
    albumTitle: 'Slippery When Wet',
    artist: 'Bon Jovi',
    tracks: ['Let It Rock', 'You Give Love a Bad Name']
  },
  2468: {
    albumTitle: '1999',
    artist: 'Prince',
    tracks: ['1999', 'Little Red Corvette']
  },
  1245: {
    artist: 'Robert Palmer',
    tracks: []
  },
  5439: {
    albumTitle: 'ABBA Gold'
  }
};

// Only change code below this line
function updateRecords(records, id, prop, value) {
  if (value === '') delete records[id][prop];
  else if (prop === 'tracks') {
    records[id][prop] = records[id][prop] || [];
    records[id][prop].push(value);
  } else {
    records[id][prop] = value;
  }

  return records;
}