js判断访问的是手机端，还是pc端

<SCRIPT LANGUAGE="JavaScript">
  <!--
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");
    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";
    } 
    return "None";
}

alert(detectOS())

  //-->
  </SCRIPT>