alt.www.webmaster Notes for Novices

 

The Ultimate Browser Sniffer

On the never ending trail of maximum compatability, while retaining javascripts, embeded Active-X components, animations, Flash and still supporting the disabled user (sheesh!) we have the following solution.

Briefly, the start page for a web site may attempt to detect the reading browser and redirect to an appropriate start page, thereby allowing IE 6 users to enjoy Flash, Mozilla users with javascript turned off to enjoy a plain HTML site etc.

The browser detection code comes from Netscape, I have just added a couple of lines to simply demonstrate redirecting to new pages if:

1) The incoming browser claims to be IE with javascript enabled

2) The incoming browser claims to be Navigator (or Mozilla) with javascript enabled

3) Stay with the current page if the browser does not have javascript enabled or is unknown. This last scenario encompasses Lynx and probably suggests a plain version of the site to be appropriate.

Netscape's code is much more detailed than perhaps is necessary, but I leave it you to remove the elements you don't want.

No its not perfect. A browser can spoof its identity, but that's not an issue. If an Opera user wants to claim to be using IE then they must accept that perhaps they wil be provided with IE optimised web pages. Support for the disabled doesn't extend as far as compulsive liars!

<HTML>
 
<HEAD>
<TITLE></TITLE>
</HEAD>
<BODY>

<SCRIPT LANGUAGE="JavaScript">
<!--
// Ultimate client-side JavaScript client sniff. Version 3.03
// (C) Netscape Communications 1999-2001.  Permission granted to reuse and distribute.
// Revised 17 May 99 to add is_nav5up and is_ie5up (see below).
// Revised 20 Dec 00 to add is_gecko and change is_nav5up to is_nav6up
//  also added support for IE5.5 Opera 4&5 HotJava3
AOLTV
// Revised 22 Feb 01 to correct Javascript Detection for IE 5.x, Opera
4,
//                      correct Opera 5 detection
//                      add support for winME and win2k
//                      synch with browser-type-oo.js
// Revised 26 Mar 01 to correct Opera detection
// Revised 02 Oct 01 to add IE6 detection

// Everything you always wanted to know about your JavaScript client
// but were afraid to ask. Creates "is_" variables indicating:
// (1) browser vendor:
//     is_nav, is_ie, is_opera, is_hotjava, is_webtv, is_TVNavigator,
is_AOLTV
// (2) browser version number:
//     is_major (integer indicating major version number: 2, 3, 4 ...)
//     is_minor (float   indicating full  version number: 2.02, 3.01,
4.04 ...)
// (3) browser vendor AND major version number
//     is_nav2, is_nav3, is_nav4, is_nav4up, is_nav6, is_nav6up,
is_gecko, is_ie3,
//     is_ie4, is_ie4up, is_ie5, is_ie5up, is_ie5_5, is_ie5_5up,
is_ie6, is_ie6up, is_hotjava3, is_hotjava3up,
//     is_opera2, is_opera3, is_opera4, is_opera5, is_opera5up
// (4) JavaScript version number:
//     is_js (float indicating full JavaScript version number: 1, 1.1,
1.2 ...)
// (5) OS platform and version:
//     is_win, is_win16, is_win32, is_win31, is_win95, is_winnt,
is_win98, is_winme, is_win2k
//     is_os2
//     is_mac, is_mac68k, is_macppc
//     is_unix
//     is_sun, is_sun4, is_sun5, is_suni86
//     is_irix, is_irix5, is_irix6
//     is_hpux, is_hpux9, is_hpux10
//     is_aix, is_aix1, is_aix2, is_aix3, is_aix4
//     is_linux, is_sco, is_unixware, is_mpras, is_reliant
//     is_dec, is_sinix, is_freebsd, is_bsd
//     is_vms
//
// See http://www.it97.de/JavaScript/JS_tutorial/bstat/navobj.html and
// http://www.it97.de/JavaScript/JS_tutorial/bstat/Browseraol.html
// for detailed lists of userAgent strings.
//
// Note: you don't want your Nav4 or IE4 code to "turn off" or
// stop working when new versions of browsers are released, so
// in conditional code forks, use is_ie5up ("IE 5.0 or greater")
// is_opera5up ("Opera 5.0 or greater") instead of is_ie5 or is_opera5
// to check version in code which you want to work on future
// versions.

    // convert all characters to lowercase to simplify testing
    var agt=navigator.userAgent.toLowerCase();

    // *** BROWSER VERSION ***
    // Note: On IE5, these return 4, so use is_ie5up to detect IE5.
    var is_major = parseInt(navigator.appVersion);
    var is_minor = parseFloat(navigator.appVersion);

    // Note: Opera and WebTV spoof Navigator.  We do strict client detection.
    // If you want to allow spoofing, take out the tests for opera and webtv.
    var is_nav  = ((agt.indexOf('mozilla')!=-1) &&
(agt.indexOf('spoofer')==-1)
                && (agt.indexOf('compatible') == -1) &&
(agt.indexOf('opera')==-1)
                && (agt.indexOf('webtv')==-1) &&
(agt.indexOf('hotjava')==-1));
    var is_nav2 = (is_nav && (is_major == 2));
    var is_nav3 = (is_nav && (is_major == 3));
    var is_nav4 = (is_nav && (is_major == 4));
    var is_nav4up = (is_nav && (is_major >= 4));
    var is_navonly      = (is_nav && ((agt.indexOf(";nav") != -1) ||
                          (agt.indexOf("; nav") != -1)) );
    var is_nav6 = (is_nav && (is_major == 5));
    var is_nav6up = (is_nav && (is_major >= 5));
    var is_gecko = (agt.indexOf('gecko') != -1);


    var is_ie     = ((agt.indexOf("msie") != -1) &&
(agt.indexOf("opera") == -1));
    var is_ie3    = (is_ie && (is_major < 4));
    var is_ie4    = (is_ie && (is_major == 4) && (agt.indexOf("msie
4")!=-1) );
    var is_ie4up  = (is_ie && (is_major >= 4));
    var is_ie5    = (is_ie && (is_major == 4) && (agt.indexOf("msie
5.0")!=-1) );
    var is_ie5_5  = (is_ie && (is_major == 4) && (agt.indexOf("msie
5.5") !=-1));
    var is_ie5up  = (is_ie && !is_ie3 && !is_ie4);
    var is_ie5_5up =(is_ie && !is_ie3 && !is_ie4 && !is_ie5);
    var is_ie6    = (is_ie && (is_major == 4) && (agt.indexOf("msie
6.")!=-1) );
    var is_ie6up  = (is_ie && !is_ie3 && !is_ie4 && !is_ie5 &&
!is_ie5_5);

    // KNOWN BUG: On AOL4, returns false if IE3 is embedded browser
    // or if this is the first browser window opened.  Thus the
    // variables is_aol, is_aol3, and is_aol4 aren't 100% reliable.
    var is_aol   = (agt.indexOf("aol") != -1);
    var is_aol3  = (is_aol && is_ie3);
    var is_aol4  = (is_aol && is_ie4);
    var is_aol5  = (agt.indexOf("aol 5") != -1);
    var is_aol6  = (agt.indexOf("aol 6") != -1);

    var is_opera = (agt.indexOf("opera") != -1);
    var is_opera2 = (agt.indexOf("opera 2") != -1 ||
agt.indexOf("opera/2") != -1);
    var is_opera3 = (agt.indexOf("opera 3") != -1 ||
agt.indexOf("opera/3") != -1);
    var is_opera4 = (agt.indexOf("opera 4") != -1 ||
agt.indexOf("opera/4") != -1);
    var is_opera5 = (agt.indexOf("opera 5") != -1 ||
agt.indexOf("opera/5") != -1);
    var is_opera5up = (is_opera && !is_opera2 && !is_opera3 &&
!is_opera4);

    var is_webtv = (agt.indexOf("webtv") != -1);

    var is_TVNavigator = ((agt.indexOf("navio") != -1) ||
(agt.indexOf("navio_aoltv") != -1));
    var is_AOLTV = is_TVNavigator;

    var is_hotjava = (agt.indexOf("hotjava") != -1);
    var is_hotjava3 = (is_hotjava && (is_major == 3));
    var is_hotjava3up = (is_hotjava && (is_major >= 3));

    // *** JAVASCRIPT VERSION CHECK ***
    var is_js;
    if (is_nav2 || is_ie3) is_js = 1.0;
    else if (is_nav3) is_js = 1.1;
    else if (is_opera5up) is_js = 1.3;
    else if (is_opera) is_js = 1.1;
    else if ((is_nav4 && (is_minor <= 4.05)) || is_ie4) is_js = 1.2;
    else if ((is_nav4 && (is_minor > 4.05)) || is_ie5) is_js = 1.3;
    else if (is_hotjava3up) is_js = 1.4;
    else if (is_nav6 || is_gecko) is_js = 1.5;
    // NOTE: In the future, update this code when newer versions of JS
    // are released. For now, we try to provide some upward
compatibility
    // so that future versions of Nav and IE will show they are at
    // *least* JS 1.x capable. Always check for JS version
compatibility
    // with > or >=.
    else if (is_nav6up) is_js = 1.5;
    // NOTE: ie5up on mac is 1.4
    else if (is_ie5up) is_js = 1.3

    // HACK: no idea for other browsers; always check for JS version
with > or >=
    else is_js = 0.0;

    // *** PLATFORM ***
    var is_win   = ( (agt.indexOf("win")!=-1) ||
(agt.indexOf("16bit")!=-1) );
    // NOTE: On Opera 3.0, the userAgent string includes "Windows
95/NT4" on all
    //        Win32, so you can't distinguish between Win95 and WinNT.
    var is_win95 = ((agt.indexOf("win95")!=-1) ||
(agt.indexOf("windows 95")!=-1));

    // is this a 16 bit compiled version?
    var is_win16 = ((agt.indexOf("win16")!=-1) ||
               (agt.indexOf("16bit")!=-1) || (agt.indexOf("windows
3.1")!=-1) ||
               (agt.indexOf("windows 16-bit")!=-1) ); 

    var is_win31 = ((agt.indexOf("windows 3.1")!=-1) ||
(agt.indexOf("win16")!=-1) ||
                    (agt.indexOf("windows 16-bit")!=-1));

    var is_winme = ((agt.indexOf("win 9x 4.90")!=-1));
    var is_win2k = ((agt.indexOf("windows nt 5.0")!=-1));

    // NOTE: Reliable detection of Win98 may not be possible. It
appears that:
    //       - On Nav 4.x and before you'll get plain "Windows" in
userAgent.
    //       - On Mercury client, the 32-bit version will return
"Win98", but
    //         the 16-bit version running on Win98 will still return
"Win95".
    var is_win98 = ((agt.indexOf("win98")!=-1) ||
(agt.indexOf("windows 98")!=-1));
    var is_winnt = ((agt.indexOf("winnt")!=-1) ||
(agt.indexOf("windows nt")!=-1));
    var is_win32 = (is_win95 || is_winnt || is_win98 ||
                    ((is_major >= 4) && (navigator.platform ==
"Win32")) ||
                    (agt.indexOf("win32")!=-1) ||
(agt.indexOf("32bit")!=-1));

    var is_os2   = ((agt.indexOf("os/2")!=-1) ||
                    (navigator.appVersion.indexOf("OS/2")!=-1) ||  
                    (agt.indexOf("ibm-webexplorer")!=-1));

    var is_mac    = (agt.indexOf("mac")!=-1);
    // hack ie5 js version for mac
    if (is_mac && is_ie5up) is_js = 1.4;
    var is_mac68k = (is_mac && ((agt.indexOf("68k")!=-1) ||
                               (agt.indexOf("68000")!=-1)));
    var is_macppc = (is_mac && ((agt.indexOf("ppc")!=-1) ||
                                (agt.indexOf("powerpc")!=-1)));

    var is_sun   = (agt.indexOf("sunos")!=-1);
    var is_sun4  = (agt.indexOf("sunos 4")!=-1);
    var is_sun5  = (agt.indexOf("sunos 5")!=-1);
    var is_suni86= (is_sun && (agt.indexOf("i86")!=-1));
    var is_irix  = (agt.indexOf("irix") !=-1);    // SGI
    var is_irix5 = (agt.indexOf("irix 5") !=-1);
    var is_irix6 = ((agt.indexOf("irix 6") !=-1) ||
(agt.indexOf("irix6") !=-1));
    var is_hpux  = (agt.indexOf("hp-ux")!=-1);
    var is_hpux9 = (is_hpux && (agt.indexOf("09.")!=-1));
    var is_hpux10= (is_hpux && (agt.indexOf("10.")!=-1));
    var is_aix   = (agt.indexOf("aix") !=-1);      // IBM
    var is_aix1  = (agt.indexOf("aix 1") !=-1);   
    var is_aix2  = (agt.indexOf("aix 2") !=-1);   
    var is_aix3  = (agt.indexOf("aix 3") !=-1);
    var is_aix4  = (agt.indexOf("aix 4") !=-1);   
    var is_linux = (agt.indexOf("inux")!=-1);
    var is_sco   = (agt.indexOf("sco")!=-1) ||
(agt.indexOf("unix_sv")!=-1);
    var is_unixware = (agt.indexOf("unix_system_v")!=-1);
    var is_mpras    = (agt.indexOf("ncr")!=-1);
    var is_reliant  = (agt.indexOf("reliantunix")!=-1);
    var is_dec   = ((agt.indexOf("dec")!=-1) ||
(agt.indexOf("osf1")!=-1) ||
           (agt.indexOf("dec_alpha")!=-1) ||
(agt.indexOf("alphaserver")!=-1) ||
           (agt.indexOf("ultrix")!=-1) ||
(agt.indexOf("alphastation")!=-1));
    var is_sinix = (agt.indexOf("sinix")!=-1);
    var is_freebsd = (agt.indexOf("freebsd")!=-1);
    var is_bsd = (agt.indexOf("bsd")!=-1);
    var is_unix  = ((agt.indexOf("x11")!=-1) || is_sun || is_irix ||
is_hpux ||
                 is_sco ||is_unixware || is_mpras || is_reliant ||
                 is_dec || is_sinix || is_aix || is_linux || is_bsd ||
is_freebsd);

    var is_vms   = ((agt.indexOf("vax")!=-1) ||
(agt.indexOf("openvms")!=-1));


// Redirect to a new start page depending upon the detected browser

if (is_ie)
{
    window.location.replace("ie.htm")
}

    if (is_nav)
{
    window.location.replace("nav.htm")
}
// -->
</SCRIPT>



<P>The browser either doesn't support Javascript, or it is undetectable so assume maximum compatibility here, with a plain HTML version of the start page.</P>
</BODY>
</HTML>


Matt Probert



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