Can I get the nth item of a firebase “query”?

Question

Firebase has some very basic query functionality with orderBy*, limitTo*, startAt(), etc. Is there a way to tell Firebase you want the

Answer 1

While you cannot access child items by index with Firebase, you can store the key of an item and use that to start a next query.

var ref = new Firebase('https://yours.firebaseio.com/items');
var lastKnownKey = null;
var firstQuery = ref.orderByKey().limitToFirst(100);
firstQuery.once('value', function(snapshot) {
  snapshot.forEach(function(childSnapshot) {
    lastKnownKey = childSnapshot.key();
  });
});

Now you have a variable lastKnownKey that has the last key you've ever seen. To get the next batch of children, you pass that value in to startAt():

var nextQuery = ref.orderByKey().startAt(lastKnownKey).limitToFirst(100);