判断设备类型

function detectOS() {

  var sUserAgent = navigator.userAgent;

	var isWin = (navigator.platform == "Win32") || (navigator.platform == "Windows");

	var isMac = (navigator.platform == "Mac68K") || (navigator.platform == "MacPPC") || (navigator.platform == "Macintosh") || (navigator.platform == "MacIntel");

	if (isMac) return "Mac";

  var isUnix = (navigator.platform == "X11") && !isWin && !isMac;

  if (isUnix) return "Unix";

  var isLinux = (String(navigator.platform).indexOf("Linux") > -1);

  if (isLinux) return "Linux";

  if (isWin) {

    var isWin2K = sUserAgent.indexOf("Windows NT 5.0") > -1 || sUserAgent.indexOf("Windows 2000") > -1;

    if (isWin2K) return "Win2000";

    var isWinXP = sUserAgent.indexOf("Windows NT 5.1") > -1 || sUserAgent.indexOf("Windows XP") > -1;

    if (isWinXP) return "WinXP";

    var isWin2003 = sUserAgent.indexOf("Windows NT 5.2") > -1 || sUserAgent.indexOf("Windows 2003") > -1;

    if (isWin2003) return "Win2003";

    var isWin2003 = sUserAgent.indexOf("Windows NT 6.0") > -1 || sUserAgent.indexOf("Windows Vista") > -1;

    if (isWin2003) return "WinVista"; 

    var isWin2003 = sUserAgent.indexOf("Windows NT 6.1") > -1 || sUserAgent.indexOf("Windows 7") > -1;

    if (isWin2003) return "Win7";

  }

  return "other"; 

}

alert(detectOS());