var user_agent = navigator.userAgent;
var isOpera = user_agent.indexOf("Opera") >= 0;
var isFirefox = user_agent.indexOf("Firefox") >= 0;
var isWin32up = user_agent.indexOf("Win32") >= 0 
	|| user_agent.indexOf("Win64") >= 0
	|| user_agent.indexOf("Windows NT") >= 0;

// disallow Opera faking IE
var isIE = !isOpera && user_agent.indexOf("MSIE") >= 0;
var isIE55up = isIE && isWin32up && user_agent.match(/MSIE ((5\.5)|[6789])/);
var isIE70up = isIE && isWin32up && user_agent.match(/MSIE ([789])/);
var isIE55dn = isIE && !isIE55up;
var browser = "other";

if (isFirefox)
	browser = "firefox";
else if (isOpera) 
	browser = "opera";
else if (isIE55up) 
	browser = "ie55p";
else if (isIE55dn) 
	browser = "ie55d";