Nested Objects into Arrays into an Object

April 16, 2023

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]}`);

>Solution :

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.