Question 51522 in Javascript Question posted in
A very good W3school tutorial can be found here.

How do I read the first element in an array when the array is a property of an object? – Javascript

I’m using IGDB’s API to get a release date for each game that is found from a search, but most games have numerous release dates, so those are all stored in an array, and that array is an object property. When I make a general API request, here is how the data is formatted:

[
    {
        "id": 5440,
        "name": "Kirby Triple Deluxe",
        "release_dates": [
            {
                "id": 16596,
                "human": "Jan 11, 2014"
            },
            {
                "id": 16598,
                "human": "May 16, 2014"
            },
            {
                "id": 250078,
                "human": "May 01, 2014"
            }
        ]
    }
]

Here is the code I used to log the entire release_dates array:

const collections = response.data;
collections.forEach(collection => {
  console.log(collection.name);
  console.log(collection.release_dates);
});

How can I read just the first element in the array? I want to view the "human" property of the first element. One thing I tried was collection.release_dates[0].human but that did not work.

EDIT: To give a bit more clarity: the error I get when I try console.log(collection.release_dates[0].human); within the forEach loop is this: TypeError: Cannot read properties of undefined (reading '0')

Tags:

4

Answers


  1. 0

    I wonder why this didn’t work according to the asker.

    let collections = [
    {
        "id": 5440,
        "name": "Kirby Triple Deluxe",
        "release_dates": [
            {
                "id": 16596,
                "human": "Jan 11, 2014"
            },
            {
                "id": 16598,
                "human": "May 16, 2014"
            },
            {
                "id": 250078,
                "human": "May 01, 2014"
            }
        ]
    },
    {
        "id": 5441,
        "name": "Kirby Triple Deluxe 2",
        "release_dates": []
    }
];
collections.forEach(collection => {
  if(collection.release_dates.length) {
    console.log(collection.release_dates[0].human);
  }
});
    Login or Signup to reply.
  2. 0

    Looks like your object is part of a top-level array itself…

    i guess you referred to that array as "collection", didnt you?

    if that array (that contains your object) is referenced under "collection" you should be able to acces it with

    collection[0]["release_dates"][0]

    Let me know if it worked

    Login or Signup to reply.
  3. 0

    In some cases if release_dates key is not present in the object, it will throw undefined error. So, you should use optional chaining.

    collection.release_dates?.[0]?.human
    Login or Signup to reply.
  4. 0

    Following up on others answers, here is one where you can also rely on fallback.

    collections.forEach(collection => {
  const releaseDate = collection?.release_dates?.[0]?.human ?? 'No release date.'
});

    ?? is called nullish coalescing operator. Even if release_dates[0] could be undefined, you can reliably fallback on "No release date." string.

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search