How to put an array value on nested array

Question

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": [ 
        "1999", 
        "Little Red Corvette" 
      ]
    },
    "1245": {
      "artist": "Robert Palmer",
      "tracks": [ ]
    },
    "5439": {
      "album": "ABBA Gold"
    }
};

var collectionCopy = JSON.parse(JSON.stringify(collection));

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

   collection[id][prop] = []; // Solve my problem

    collection[id][prop].push(value);
  } 
  if (!!value && prop === 'artist') collection[id][prop] = value;
  return collection;
}

updateRecords(5439, "tracks", "Take a Chance on Me");

This is original code that return an error. This is an edited and please ignore this question thanks. Trying to fix the error saying push is undefined function. You can't push an value on array object if Undefined so I put the

collection[id][prop] = []; // Solve my problem

to avoid getting error saying push is undefined on this line of code....

collection[id][prop].push(value);

This is the problem = "If prop does contain the key "tracks" and its value is non-blank, then push the value onto the end of its existing tracks array." — Raul Ventura Berina
– Raul Ventura Berina, Commented Jun 22, 2016 at 13:13

Nikhil Aggarwal · Accepted Answer · 2016-06-22 13:07:51Z

3

Try following

collection["5439"].tracks = ["some info", "some more info"];

answered Jun 22, 2016 at 13:07

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Nikhil Aggarwal

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Comments

Aditya Singh · Accepted Answer · 2016-06-22 13:13:47Z

0

You have an object collection and in order to access/ update the object you can use either . or [] notations. In order to use . notation, the key need to be a valid identifier. The number identifier "5439" is not a valid identifier and will give a SyntaxError. The safe way of doing this is using the [] notation as below:

collection["5439"]["tracks"] = [1, 2, 3, "a", "b"];

answered Jun 22, 2016 at 13:13

Aditya Singh

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2 Comments

Raul Ventura Berina Over a year ago

Thank you guys, my problem was solve, This is something to do with push() function is undefined. You can't use push() on undefined array

Raul Ventura Berina Over a year ago

Original Task = "If prop does contain the key "tracks" and its value is non-blank, then push the value onto the end of its existing tracks array."

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