Getting values from objects that are in an array of an array

Question

Let's say I have an array like so...

const myCustomers = [
    {
        accounts: [
            {
                accountID: 1234
            },
            {
                acountID: 2345
            }
        ]
    },
    {
        accounts: [
            {
                accountID: 3456
            }
        ]
    },
    {
        accounts: [
            {
                accountID: 4567
            },
            {
                accountID: 5678
            }
        ]
    }
];

I'm basically just trying to create an array of all the accountIDs, so it looks something like this...

const accountIDs = [1234, 2345, 3456, 4567, 5678];

I've tried using map but I'm not having luck.

const myRes = myCustomers.map(a => a.accounts.accountID);

palaѕн · Accepted Answer · 2020-03-18 17:48:47Z

4

You can do this using map() & flat():

myCustomers.map(c => c.accounts).flat().map(c => c.accountID)

DEMO:

const myCustomers=[{accounts:[{accountID:1234},{accountID:2345}]},{accounts:[{accountID:3456}]},{accounts:[{accountID:4567},{accountID:5678}]}];  
const result = myCustomers.map(c => c.accounts).flat().map(c => c.accountID);
console.log( result )

Or, a better approach using flatMap():

myCustomers.flatMap(c => c.accounts).map(c => c.accountID)

The flatMap() method basically first maps each element using a mapping function, then flattens the result into a new array. It is identical to a map() followed by a flat(), but flatMap() is often quite useful, as merging both into one method is slightly more efficient.

DEMO:

const myCustomers=[{accounts:[{accountID:1234},{accountID:2345}]},{accounts:[{accountID:3456}]},{accounts:[{accountID:4567},{accountID:5678}]}];  
const result = myCustomers.flatMap(c => c.accounts).map(c => c.accountID);
console.log( result )

edited Mar 18, 2020 at 17:48

answered Mar 18, 2020 at 17:40

palaѕн

74.2k17 gold badges123 silver badges140 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

TheJason Over a year ago

Thanks... this did exactly what I needed.

Collectives™ on Stack Overflow

Getting values from objects that are in an array of an array

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related