title: Firebase query in desc order based on timestamp
body: <p>I am having trouble returning an array of objects in desc order from firebase and javascript with react native. I am essentially "joining" two firebase parents and then pushing them into an array. </p>
  
  <pre><code>async loadChats(userId){
  
   this.chatIdRef = firebase.database().ref("members");
   this.chatIdRef.off();
   this.chatsRef = firebase.database().ref("chats");
   this.chatsRef.off();
  
   items = [];
   this.chatIdRef.child(userId).on('child_added', snap =&gt; {
   this.chatsRef.child(snap.key).startAt().on('value', snapshot =&gt; {
  
      items.push({
        receiverId: snap.val().userId,
        timeStamp: snapshot.val().createdAt,
        name: snap.val().userName,
        key: snapshot.key
      });
  
    this.setState({
      dataSource: this.state.dataSource.cloneWithRows(items)
    });
  
    });
   });
  }
  </code></pre>
  
  <p>I have tried using "orderByChild('createdAt')" in my query but no luck.</p>