var sUserAgent = navigator.userAgent; //浏览器判断值
//检测Opera、KHTML
var isOpera = sUserAgent.indexOf("Opera") > -1;
var isKHTML = sUserAgent.indexOf("KHTML") > -1 || sUserAgent.indexOf("Konqueror") > -1 || sUserAgent.indexOf("AppleWebKit") > -1;
//检测IE、Mozilla
var isIE = sUserAgent.indexOf("compatible") > -1 && sUserAgent.indexOf("MSIE") > -1 && !isOpera;
var isMoz = sUserAgent.indexOf("Gecko") > -1 && !isKHTML;
//检测操作系统
//navigator.platform 运行浏览器的计算机平台的字符串表示
var isWin = (navigator.platform == "Win32") || (navigator.platform == "Windows");
var isMac = (navigator.platform == "Mac68K") || (navigator.platform == "MacPPC") || (navigator.platform == "Macintosh");
var isUnix = (navigator.platform == "X11") && !isWin && !isMac;
if (isOpera) document.write("Opera ");
if (isKHTML) document.write("KHTML ");
if (isIE) document.write("IE ");
if (isMoz) document.write("Mozilla ");
if (isWin) document.write("Windows");
if (isMac) document.write("Mac");
if (isUnix) document.write("Unix");