// with once('value')
firebase().database().ref('/dinosaurs').orderByChild('height').once('value', function (snapshot) {
  snapshot.forEach(function(child) {
      console.log(child.val())
  });
});

// OR with once('child_added')
firebase().database().ref('/dinosaurs').orderByChild('height').once('child_added', function (snapshot) {
	   console.log(snapshot.val());
})