javascript - Firebase promise - Query.once failed: Was called with 1 argument. Expects at least 2

Question

I'm trying to fill an array with some data from Firebase using promises. Here's the DB structure:

- domain name(or something)
  |--highscore
     |--Foo: 50
     |--Bar: 60

The code:

var arr=[];
highscoreRef.child('highscore').once('value').then(function(snapshot) {
    snapshot.forEach(function(data) {
    arr.push({playerName: data.key(), score: data.val()});
    });
  }, function(error) {
     console.error(error);
});

I get Uncaught Error: Query.once failed: Was called with 1 argument. Expects at least 2.

Does that mean I have to add at least 2 properties to Foo and Bar? Ex. Foo = {playerName: name, score: 50}

The current DB arrangement fits my needs.

Answer 1

Waitting for answers