title: get height for a div with overflow:auto;
body: <p>i have a div with height:100px and overflow:auto
  the content is dynamic.</p>
  
  <p>i want scroll the div in the bottom</p>
  
  <p>i tried with</p>
  
  <pre><code>$("#chat_content").scrollTop($("#chat_content").height());
  </code></pre>
  
  <p>but if the content is bigger than 100px 
  $("#chat_content").height() returns 100 and the div isn't scrolled on the bottom </p>
  
  <p>how can i do?</p>
  
  <p>thanks</p>