Multi document creation in sub-collection in Firestore I am trying to write a function that will:

*

*Create documents in a sub collection

*Allow for a then/catch call back after all sub documents have been created

    export const doCreateSubs = (Id, count) => {
if (count > 0 && count <= 50){
const times = n => f => {
let iter = i => {
if (i === n) return;
f(i);
iter(i + 1);
};
return iter(0);
};
times(count)(i => {
db
.collection("parent")
.doc(`${Id}`)
.collection("sub")
.add({ 
subName: `name ${i + 1}`, 
dateCreated: new Date() 
});
});
}
    }

I've played around with batch but it doesn't work with .collection. I know my function is really poor - is there a generally bettery way of doing this?

So i've just realised you can .doc() with no value and it will create a uid for the key. I can also return .commit and recieve a call back when it's complete!
export const doCreateSubs = (Id, count) => {
    if (count > 0 && count <= 50){

const times = n => f => {
let iter = i => {
if (i === n) return;
f(i);
iter(i + 1);
};
return iter(0);
};

const batch = db.batch();

times(count)(i => {

const ref = db
.collection("parent")
.doc(`${Id}`)
.collection("subs")
.doc();

batch.set(ref, {
boxName: `Sub ${i + 1}`, 
dateCreated: new Date()
});

});

return batch.commit();
    }
}