firebase_snapshot_parent.js

function getParent(snapshot) {
  // You can get the reference (A Firebase object) from a snapshot
  // using .ref().
  var ref = snapshot.ref();
  // Now simply find the parent and return the name.
  return ref.parent().name();
}

var testRef = new Firebase("https://example.firebaseIO-demo.com/foo/bar");
testRef.once("value", function(snapshot) {
  // Should alert "Name of the parent: foo".
  alert("Name of the parent: " + getParent(snapshot));
});