lastIndexOf does not work in Internet Explorer
<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>
