Question 50240 in Javascript Question posted in
A very good W3school tutorial can be found here.

Nested Objects into Arrays into an Object – Javascript

I would need help to access the value of a key-value pair from an object that is itself nested into an array (several objects with 2 key-value pairs inside an array Several arrays into an object).

So for example, I would need to access only one of the names such as Max or Lucas…

I tried to access it but no luck… Any help would be much appreciated.

const nested = {
    40: [
        { hello: "1", name: "Max" },
        { hello: "2", name: "Julie" },
        { hello: "3", name: "Mark" },
        { hello: "4", name: "Isabella" },
    ],
    50: [
        { hello: "1", name: "William" },
        { hello: "2", name: "James" },
        { hello: "3", name: "Lucas" },
        { hello: "4", name: "John" },
    ],
};


// Here is what I tried but I didn't find any way to access a console.log that would return only a // single in the output.


const keysHello = Object.keys(nested);
console.log("keysHello", keysHello); // ['40', '50']

const values = Object.values(nested);
console.log("values", values); // [[{…}, {…}, {…}, {…}], [{…}, {…}, {…}, {…}])]

const keysValues = Object.entries(nested);
console.log("keysValues", keysValues); // [['40', [{…}, {…}, {…}, {…}]], ['50', [{…}, {…}, {…}, {…}]]

// The one below does not work
// const [, , {name}] = nested;
// console.log(`${Object.values[40]}`);
Tags:

2

Answers


  1. 0

    If you know the key and the index you need to access, you can just do nested['40'][0].name for instance.

    More generic:

    const nested = {
    40: [
        { hello: "1", name: "Max" },
        { hello: "2", name: "Julie" },
        { hello: "3", name: "Mark" },
        { hello: "4", name: "Isabella" },
    ],
    50: [
        { hello: "1", name: "William" },
        { hello: "2", name: "James" },
        { hello: "3", name: "Lucas" },
        { hello: "4", name: "John" },
    ],
};

const key = '40';
const index = 0;

const { name } = nested[key][index];

    See how you cannot do nested.40, as numeric values cannot be used with dot notation.

    Login or Signup to reply.
  2. 0

    You seem to be getting confused on what you’re working with here. You have an object first, so const [, , {name}] = nested; wouldn’t do anything. It’s an object, not an array.

    Same for Object.values[40]. With that one you have an array of objects, so there’s no object at that location to get values on. Anyway you’re using Object.values incorrectly there. You would do something like Object.values(nested['40'][0]).

    Try:

    console.log(nested['40']);
console.log(nested['40'][0]);
console.log(Object.values(nested['40'][0]));

    Also worth mentioning that although you are trying to work with numbers, those are used for arrays and numbers are coerced (changed) to strings here (when working with object keys). So it’s best to just work with strings directly to avoid confusion.

    const nested = {
    '40': [
        { hello: "1", name: "Max" },
        { hello: "2", name: "Julie" },
        { hello: "3", name: "Mark" },
        { hello: "4", name: "Isabella" },
    ],
    '50': [
        { hello: "1", name: "William" },
        { hello: "2", name: "James" },
        { hello: "3", name: "Lucas" },
        { hello: "4", name: "John" },
    ],
};
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search