title: get more data after some given id in firebase
body: <p>I'm new using firebase and I'd like to make an infinite scroll pagination to my posts.</p>
  
  <p>Suppose I have this post IDS:</p>
  
  <pre><code>-M5HMGs3EnBv6O2NSxG
  -M5HMGsA3YyW_NJ3fSV
  -M5HMGsdfLOOEPPBR_s
  -M5HMGsiH9HIZw9DNaz
  -M5HMHFYoUX8kNolLrP
  -M5HMHFZvDrV27S2hSt
  -M5HMHFnrQ_l4mVQ0rX
  -M5HMHFoaV8wbexwPCd
  -M5HMJQaaFGxF450lJB
  -M5HMJQe319R19Cvak6 // THE LAST ONE IN FIRST PAGINATION
  -M5HMJQh2gWuah7GSht
  -M5HMJQlrcfTTF3fbbI
  -M5HMJQo6QT1HwWP2lz
  -M5HMJQrIUiZyzhiqK3
  -M5HMJQudSkFdvs42D1
  -M5HMJRCmbFbxKp1NgA
  -M5HMJRFwfo7yN8Is3-
  -M5HMJRIsKT3YmoukQ0
  -M5HMJRKDTq7XuqtshT
  -M5HMJRNRabXbYQUMi6
  -M5HMJRS1t9UBzH_3Jh
  -M5HMJRXEv6BaPeQPMn
  -M5HMJR_bRdxCBy-uma
  -M5HMJRdOPBA-SMoMjB
  </code></pre>
  
  <p>So, first I get the first 10 posts till the id <code>M5HMJQe319R19Cvak6</code> using this:</p>
  
  <pre><code>var starCountRef = firebase.database().ref('/posts/').limitToFirst(11);
  </code></pre>
  
  <p>it is ok. When I go to the last post my reactjs will call this function again sending the last loaded post ID (the M5HMJQe319R19Cvak6) in variable <code>pageNumber</code>.</p>
  
  <p>What I'd like to do is get posts after this last id given to continue the pagination, like so:</p>
  
  <pre><code>-M5HMJQh2gWuah7GSht
  -M5HMJQlrcfTTF3fbbI
  -M5HMJQo6QT1HwWP2lz
  -M5HMJQrIUiZyzhiqK3
  -M5HMJQudSkFdvs42D1
  ...
  </code></pre>
  
  <p>I tried to use startAt(ID) but no result has shown:</p>
  
  <pre><code>var starCountRef = firebase.database().ref('/posts/').limitToFirst(11).startAt(pageNumber);
  </code></pre>
  
  <p>any ideas how can I get posts after an id in firebase?</p>