converting an array into object in typescript

I have an array of objects:

const users: Person[] = [{name: 'Erich', age: 19}, {name: 'Johanna', age: 34}, {name: 'John', age: 14}];

Where

interface Person {
    age: number;
    name: string;
};

I need to convert it to the type NFCollection which looks so:

interface NFCollection {
    type: string;
    data: Person[];
}

The result should looks like this:

const nfCollection: NFCollection = {
    type: 'adults',
    data: [{name: 'Erich', age: 19}, {name: 'Johanna', age: 34}]
}

where the data includes only those persons whose age >= 18.

So I could start writing something like:

const nfCollection: NFCollection = users.filter(u => u.age >= 18); // something else should follow the chain?

but then I would like to convert it to the NFCollection type. How would I do that? Preferably in a memory efficient way, cos the array could be relatively big.

Answer

Just put the filtered array as a property of a new object?

const nfCollection = {
    type: 'adults',
    data: users.filter(u => u.age >= 18)
};

Then nfCollection will have the same type as your NFCollection interface.