Untitled

HTML How to check which browser is the html currently being viewed in?
<!--[if lt IE 7]>      <html class="ie6"> <![endif]-->
<!--[if IE 7]>         <html class="ie7"> <![endif]-->
<!--[if IE 8]>         <html class="ie8"> <![endif]-->
<!--[if gt IE 8]><!--> <html>         <!--<![endif]-->

<!-- paulirish.com/2008/conditional-stylesheets-vs-css-hacks-answer-neither/ -->
<!--[if lt IE 7]> <html class="no-js lt-ie9 lt-ie8 lt-ie7" lang="en"> <![endif]-->
<!--[if IE 7]>    <html class="no-js lt-ie9 lt-ie8" lang="en"> <![endif]-->
<!--[if IE 8]>    <html class="no-js lt-ie9" lang="en"> <![endif]-->
<!-- Consider adding a manifest.appcache: h5bp.com/d/Offline -->
<!--[if gt IE 8]><!--> <html class="no-js" lang="en"> <!--<![endif]-->

<!DOCTYPE html>
<html>
<head><title>test</title></head>
<body>
<script>
alert(navigator.userAgent);
</script>
</body>
</html>