次のJavaScriptは、Internet Explorerのバージョン8,7または6を検出するために使用されます。ブラウザがInternet Explorerでない場合は、-1が返されます。 

function getInternetExplorerVersion()//Returns the version of Windows Internet Explorer or a -1//(indicating the use of another browser).
{
   var rv = -1;//Return value assumes failure.
   if (navigator.appName == 'Microsoft Internet Explorer')
   {
      var ua = navigator.userAgent;
      var re  = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
      if (re.exec(ua) != null)
         rv = parseFloat( RegExp.$1 );
   }
   return rv;
}
function checkIEVersion()
{
   var msg = "You're not using Windows Internet Explorer.";
   var ver = getInternetExplorerVersion();
   if ( ver> -1 )
   {
      if ( ver>= 8.0 )
         msg = "You're using Windows Internet Explorer 8.";
      else if ( ver == 7.0 )
          msg = "You're using Windows Internet Explorer 7.";
      else if ( ver == 6.0 )
          msg = "You're using Windows Internet Explorer 6.";
      else
          msg = "You should upgrade your copy of Windows Internet Explorer";
    }
   alert( msg );
}

リファレンス


http://msdn.microsoft.com/en-us/library/cc817582.aspx

リンク://タグ/javascript/[javascript]