Basic JavaScript - Record Collection

Tell us what’s happening:
I just confuse because when i try to set prop to value, i will not get the answer. After i look on other’s hint, they will use records[id][prop] to set the prop to value. Why we use this method, as it looks like 2d array and why not just use @ recordCollection[id][prop]? Thank you.

Your code so far

// 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) {

  if (prop != "tracks" && value != ""){ = value;


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

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/ Safari/537.36

Challenge: Basic JavaScript - Record Collection

Link to the challenge:

You can not reference because there is no property named “id” in recordCollecction. You would be referencing undefined and attempting to reference any property on undefined would result in an error as undefined does not have properties.

I strongly suggest you to review the following challenges and then try to work through this challenge again.

ouh, i see why… Thanks for the explaination and the suggestion though :+1: