title: lastIndexOf does not work in Internet Explorer
body: <p>I have the following code:</p>
  
  <pre><code>        var currentServerlist = [];
          var newServerIp = document.getElementById('add_server').value; 
          if( CurrentServerIP != newServerIp )
          {
              $('#failoverServers td.row_selector').each(function() {
              var row = $(this).closest('tr');
              var serverIp = row.find('td[rel=ip]').text();
              currentServerlist.push(serverIp);   
              });
  
              if(currentServerlist.lastIndexOf(newServerIp) != -1)
              {
                  return true;
              }
              return false;
           }
  </code></pre>
  
  <p>But I find that the lastIndexOf does not work in InternetExplorer (It does in Chrome).</p>
  
  <p>How can I fix this?</p>