JavaScript Record Collection Challenge Solution

The FreeCodeCamp Record Collection challenge allows you to test your understanding of JavaScript algorithms and data structures.

In this challenge, you are given a JSON object that represents a part of your music album collection.

There’s an updateRecords() function that can be used to modify the record collection object. It accepts 4 parameters:

• The records collection object
• The id of the record you want to modify
• The prop that determines the type of the value (either tracks, artist, or albumTitle)
• And the value to add

You are given the task to update the updateRecords() function with the following requirements:

• The function must always return the entire JSON object
• If prop is not tracks and value is not an empty string, add a new property to the album with the same name as prop with value as its value
• If prop is tracks but the album doesn’t have a tracks property, create the tracks property as an empty array and add the value to it
• if prop is tracks and value is not an empty string, add value to the end of the tracks array
• if value is an empty string, delete the prop key from the album object.

The challenge gives you the following starting point:

// 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");

To solve this challenge, you need to update the updateRecords() function given above.

You need to understand JavaScript conditional if..else block and hasOwnProperty() object method

Challenge solution

The first thing you need to do here is to check on the value of the value parameter passed to the function.

If the value parameter is an empty string, you delete the prop of the object with the same id value passed as an argument to the function.

Here’s how you do it:

function updateRecords(records, id, prop, value) {
  if (value === "") {
    delete records[id][prop];
  }
  return records;
}

In the above code, the bracket notation [] is used to access the object’s properties ([id] and [prop])

Next, you need to check if the prop variable value is equal to tracks or not.

If it’s not, then you just add the prop as a new property to the object as follows:

function updateRecords(records, id, prop, value) {
  if (value === "") {
    delete records[id][prop];
  } else if (prop !== "tracks") {
    records[id][prop] = value;
  }
  return records;
}

When the prop value equals the string tracks, you need to check if the record with the same id value has the tracks property.

When the object has the tracks property, add the value to the tracks array using the push() method:

function updateRecords(records, id, prop, value) {
  if (value === "") {
    delete records[id][prop];
  } else if (prop !== "tracks") {
    records[id][prop] = value;
  } else {
    if (records[id].hasOwnProperty("tracks")) {
      records[id].tracks.push(value);
    }
  }
  return records;
}

Finally, you need to create a new tracks property to the object when it doesn’t have one as follows:

function updateRecords(records, id, prop, value) {
  if (value === "") {
    delete records[id][prop];
  } else if (prop !== "tracks") {
    records[id][prop] = value;
  } else {
    if (records[id].hasOwnProperty("tracks")) {
      records[id].tracks.push(value);
    } else {
      records[id].tracks = [];
      records[id].tracks.push(value);
    }
  }
  return records;
}

With that, the updateRecords() function is now finished.

Run the tests to see your code pass all presented scenarios.

Congratulations on passing the challenge! 😉 This challenge should improve your understanding of JavaScript control flow with if..else block and manipulating an object.