function getInternetExplorerVersion(){
   var rv = -1;
       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;
}
var ver = getInternetExplorerVersion();
	  if(ver> -1){
		    if(ver == 8.0){
			      alert("您好,您的浏览器版本过低,请升级后操作,谢谢合作!");
			      return false;
		  }
	}
原文:http://www.cnblogs.com/xushuyi/p/4475321.html