var ns= (navigator.appName.substring(0,8)=="Netscape");
var ie= (navigator.appName.indexOf('Microsoft Internet Explorer')>-1);
var ns4= (ns && (navigator.appVersion.charAt(0)==4));
var ns6plus= (ns && (navigator.appVersion.charAt(0)>4)); //true for NS6 and NS7
var ie5plus= (ie && ((navigator.userAgent.indexOf("MSIE 5")!=-1)||(navigator.userAgent.indexOf("MSIE 6")!=-1)));
var ns7= (ns && (navigator.userAgent.indexOf("Netscape/7"))!=-1);
var opera=(ie && (navigator.userAgent.indexOf("Opera"))!=-1);
var firefox=(ns && (navigator.userAgent.indexOf("Firefox"))!=-1);

var b="";  // browser type
if (ns) {
 if (firefox) b="Firefox_"+navigator.userAgent.charAt(navigator.userAgent.indexOf("Firefox")+8);
 else if (ns7) b="Netscape_7";
 else if (ns4) b="Netscape_4";
 else if (ns6plus) b="Netscape_"+navigator.appVersion.charAt(0);
}
else if (ie) {
 if (opera) b="Opera_"+navigator.userAgent.charAt(navigator.userAgent.indexOf("Opera")+6);
 else if (ie5plus) b="MSIE_"+navigator.userAgent.charAt(navigator.userAgent.indexOf("MSIE")+5);
}