title: Get Firebase child nodes' names without getting their children too in Firebase response?
body: <p>I have the following hierarchy on firebase, some data are hidden for confidentiality:</p>
  
  <p><img src="https://i.stack.imgur.com/Ewvz6.png" alt="enter image description here"> </p>
  
  <p>I'm trying to get a list of videos IDs (underlines in red)<br></p>
  
  <p>I only can get all nodes, then detect their names and store them in an array!<br> 
  But this causes low performance; because the <code>dataSnapshot</code> from firebase is very big in my case, so I want to avoid retrieving all the nodes' content then loop over them to get IDs, I need to just retrieve the IDs only, i.e. without their nested elements.</p>
  
  <p>Here's my code:</p>
  
  <pre><code>new Firebase("https://PRIVATE_NAME.firebaseio.com/videos/").once(
      'value', 
      function(dataSnapshot){ 
  
          // dataSnapshot now contains all the videos ids, lines &amp; links
          // this causes many performance issues
  
          // Then I need to loop over all elements to extract ids !
          var videoIdIndex = 0;
          var videoIds = new Array();
  
          dataSnapshot.forEach(
              function(childSnapshot) {
                  videoIds[videoIdIndex++] = childSnapshot.name();
              }
          );
  
      }
  );
  </code></pre>
  
  <p><strong>How may I retrieve only IDs to avoid lot of data transfer and to avoid looping over retrived data to get IDs ? is there a way to just retrive these IDs directly ?</strong> </p>