<script type="text/javascript">
var browsername = navigator.appName;
var browserversion = navigator.appVersion;
var browserdetail = browsername+browserversion;
if (browserdetail.indexOf(' ')!=-1)
{
alert(its working!);
}
</script>
Inside indexOf(''), you can mention the browser name with version (e.g. MSIE 6.0).
thank you ... bye