I have an array of objects (myObjsArr). The object contains 2 methods:

obj: {
   getUserId(), // returns a string. For instance, "123"
   getSubUserIds(), // returns an array of strings. For instance, ["abc", "abc2", ...]
}

I'm looping this array of objects to create 2 arrays.

1. Array of user ids
2. Array of sub user ids.

const userIds = [];
const subUserIds = [];

myObjsArr.forEach((obj) => {
   userIds.push(obj.getUserId());
   obj.getSubUserIds(element => {
      subUserIds.push(element);
   })
});

This works, but seems not efficient. How could I improve my code?

Thanks