Record Collection Challenge Confusion

I’m getting this error:

“Cannot read property ‘push’ of undefined”

I don’t understand what’s happening, and I appreciate any help.

Your code so far

// Setup
var collection = {
    "2548": {
      "album": "Slippery When Wet",
      "artist": "Bon Jovi",
      "tracks": [ 
        "Let It Rock", 
        "You Give Love a Bad Name" 
    "2468": {
      "album": "1999",
      "artist": "Prince",
      "tracks": [ 
        "Little Red Corvette" 
    "1245": {
      "artist": "Robert Palmer",
      "tracks": [ ]
    "5439": {
      "album": "ABBA Gold"
// Keep a copy of the collection for tests
var collectionCopy = JSON.parse(JSON.stringify(collection));

// Only change code below this line

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

  return collection;

// Alter values below to test your code
updateRecords(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/67.0.3396.99 Safari/537.36.

Link to the challenge:

Your code above is on the right track. However, what if there currently is no “tracks” property in collection[id} ? That means there is no array present for you to push values into. If there is no property, you could first add a blank array to a “tracks” property and then use the push method to push into it.

Hint: You can probably use the hasOwnProperty method here in some way.

1 Like

Very helpful! Thank you!