Detecting browsers javascript hacks

Thursday, 29 January 2009

I enjoyed my last experiment to create tiny browser detection hacks, so I thought I’d try and do some more in other browsers. I’ve found these while testing Hackvertor and writing the inspection functions. The rules are simple if you want to post your own:-

1. The variable assignment must be the abbreviation of the browser. E.g. FF, IE, Op, Saf, Chr.
2. The detection shouldn’t be able to be overwritten. E.g. IE=!!top.execScript is incorrect because a web site can redefine execScript as a variable or function.
3. Small and as fast as possible please.

To start off, this one was found by DoctorDan from the slackers forums:-

//Firefox detector 2/3 by DoctorDan
FF=/a/[-1]=='a'

//Firefox 3 by me:-
FF3=(function x(){})[-5]=='x'

//Firefox 2 by me:-
FF2=(function x(){})[-6]=='x'

//IE detector I posted previously
IE='\v'=='v'

//Safari detector by me
Saf=/a/.__proto__=='//'

//Chrome by me
Chr=/source/.test((/a/.toString+''))

//Opera by me
Op=/^function \(/.test([].sort)

//IE6 detector using conditionals 
try {IE6=@cc_on @_jscript_version <= 5.7&&@_jscript_build<10000} catch(e){IE6=false;}

As I come across more developing Hackvertor I shall post them here. Please post your own or verify any of the ones posted.

Update...

One line to rule them all:-

B=(function x(){})[-5]=='x'?'FF3':(function x(){})[-6]=='x'?'FF2':/a/[-1]=='a'?'FF':'\v'=='v'?'IE':/a/.__proto__=='//'?'Saf':/s/.test(/a/.toString)?'Chr':/^function \(/.test([].sort)?'Op':'Unknown'

The entry 'Detecting browsers javascript hacks' was posted on January 29th, 2009 at 9:26 am and last modified on July 13th, 2009 at 8:32 am, and is filed under javascript. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

41 Responses to “Detecting browsers javascript hacks”

  1. est writes:
    No. 1 — January 29th, 2009 at 10:01 am

    Nice!

  2. Dave writes:
    No. 2 — January 29th, 2009 at 11:26 am

    That is pretty epic I wont lie. *Blogs this*

  3. Gareth Heyes writes:
    No. 3 — January 29th, 2009 at 11:52 am

    I can make it smaller if you’re not interested in which version of FF:-

    B=/a/[-1]==’a’?’FF’:’\v’==’v’?’IE’:/a/.__proto__==’//’?’Saf’:/s/.test(/a/.toString)?’Chr’:’Op’

    //94!

  4. Ben writes:
    No. 4 — January 29th, 2009 at 2:07 pm

    This is pretty insane, man!

    I sure do hope it gets implemented in jQuery’s and the other libraries’ cores…

  5. Sam writes:
    No. 5 — January 29th, 2009 at 2:36 pm

    It gives ‘Op’ in FF3.1 beta2.

  6. Gareth Heyes writes:
    No. 6 — January 29th, 2009 at 2:47 pm

    @Sam

    I’ve updated the one rule, please try again. If you can please run this hackvertor code to see what results in FF3.1 beta :-

    http://www.businessinfo.co.uk/labs/hackvertor/hackvertor.php?input=Ly9DbGljayAiaW5zcGVjdCBvdXRwdXQiCmFsZXJ0

  7. Keenora writes:
    No. 7 — January 30th, 2009 at 9:08 am

    Another little change would be a CSS-Selector in 252 Bytes:

    document.getElementsByTagName(‘html’)[0].className+=’ ‘+(function x(){})[-5]==’x’?’FF3′:(function x(){})[-6]==’x’?’FF2′:/a/[-1]==’a’?’FF’:’\v’==’v’?’IE’:/a/.__proto__==’//’?’Saf’:/s/.test(/a/.toString)?’Chr’:/^function \(/.test([].sort)?’Op’:’Unknown’

    You can use:

    .IE .example { color: red; }
    .FF2 . example { color: lime; }
    etc…
    (classNames are case sensitive!)

    Have fun 🙂

  8. Graham writes:
    No. 8 — January 30th, 2009 at 10:03 am

    One obvious point is that browser detection is something that should be avoided wherever possible – feature detection should be used instead otherwise your website won’t work on the next browser released…

  9. kangax writes:
    No. 9 — January 31st, 2009 at 3:31 am

    Opera test doesn’t quite satisfy your rules, as it can be easily overwritten:

    Array.prototype.sort.toString = function(){ return ‘function (){}’ }

    /^function \(/.test([].sort); // true

  10. kangax writes:
    No. 10 — January 31st, 2009 at 3:35 am

    Safari check can be fooled in the very same way, of course:

    RegExp.prototype.toString = function(){ return ‘//’ };
    /a/.__proto__==’//’; // true

  11. Paul Irish writes:
    No. 11 — February 4th, 2009 at 6:45 pm

    These are most excellent. I just used a few in a bookmarklet for adding new css rules to the page

    The safari test only catches safari proper and not the webkit-also Chrome… Do you have a clever solution to catch both? (I recognize they’re different js engines, but come on.. you’re clever. 🙂

  12. Gareth Heyes writes:
    No. 12 — February 4th, 2009 at 10:33 pm

    @Paul

    I’ve not got Chrome handy at the moment because I’m on a different computer. However this should work:-

    WebKit=typeof document.body.style.WebkitAppearance==’string’;

    This can be overwritten though so technically it breaks the rules but it might be good enough for what you want.

  13. Gareth Heyes writes:
    No. 13 — February 5th, 2009 at 2:06 pm

    Just to confirm it does work in Chrome and Safari 😀

  14. Paul Irish writes:
    No. 14 — February 6th, 2009 at 6:35 pm

    Gareth, you are a machine. Well done.

  15. Ehsun Amanolahi writes:
    No. 15 — March 16th, 2009 at 1:06 pm

    Nice stuff!

  16. asf writes:
    No. 16 — April 8th, 2009 at 10:53 pm

    The Opera test does not work in 9.2x

  17. Gyrobo writes:
    No. 17 — April 24th, 2009 at 8:51 pm

    IE=@cc_on true ? true : @false;

    Internet Explorer supports <a href=”http://msdn.microsoft.com/en-us/library/ahx1z4fs(VS.80).aspx”>conditional compilation</a> which can be used to accurately detect its version:

    IE8=@cc_on @_jscript_version == 5.8 ? true : @false

    IE7=@cc_on @_jscript_version == 5.7 ? true : @false

    IE6=@cc_on @_jscript_version == 5.6 ? true : @false

    IE55=@cc_on @_jscript_version == 5.5 ? true : @false

  18. Gyrobo writes:
    No. 18 — April 24th, 2009 at 8:53 pm

    My asterisks and slashes have vanished.

    There should be a block comment opened right before each @cc_on, and closed after the final @.

  19. Gareth Heyes writes:
    No. 19 — April 25th, 2009 at 6:44 am

    @Gyrobo

    Sorry about that I remove comments from WordPress to avoid SQL injection attacks.

    Conditional comments work well but not when the code is compressed

  20. 布里斯班 writes:
    No. 20 — April 25th, 2009 at 1:12 pm

    Quite a great effect.
    Thanks for sharing.

  21. Gyrobo writes:
    No. 21 — April 28th, 2009 at 12:37 pm

    Well then, I guess I learned something about both compression and SQL injection. Yay!

  22. Инокентий writes:
    No. 22 — June 25th, 2009 at 12:38 pm

    Хорошая статья, больше бы таких!

  23. Димитрий writes:
    No. 23 — July 31st, 2009 at 11:17 am

    А подробнее можно?

  24. Gareth Heyes writes:
    No. 24 — July 31st, 2009 at 11:51 am

    Да, больше невозможно. Попробуйте JavaScript обнаружения CSS свойства как МОЗ или MS-т.д.

  25. d writes:
    No. 25 — August 4th, 2009 at 4:33 pm

    hello,

    great stuff! it seems that the one line detector is just returning ‘FF’ for firefox 3.5.1 mac+win. Any chance of a fix?

    best,
    -D

  26. Gareth Heyes writes:
    No. 26 — August 4th, 2009 at 5:01 pm

    @d

    This should detect FF3.5 and above:-

    FF3=(/a/[-1]&&Object.getPrototypeOf)?true:false

  27. Kyle Simpson writes:
    No. 27 — December 1st, 2009 at 3:47 pm

    Just wanted to share two hacks I’m currently using (in LABjs) for detecting Firefox(Gecko) and for detecting Opera:

    is_opera = window.opera && Object.toString.call(window.opera) == “[object Opera]”

    is_gecko = (function(o) { o[o] = o+””; return o[o] != o+””; })(new String(“__count__”))

  28. d writes:
    No. 28 — December 1st, 2009 at 7:22 pm

    @gareth:
    thanks brother!

  29. Mathias Bynens writes:
    No. 29 — December 17th, 2009 at 12:14 pm

    The IE check can be shortened to:

    IE=!+'\v1';
  30. Gareth Heyes writes:
    No. 30 — December 17th, 2009 at 12:28 pm

    @Mathias

    Yeah someone already pointed that out:-

    http://sla.ckers.org/forum/read.php?2,15812,26331,page=13#msg-26331

  31. Dmitry Binner writes:
    No. 31 — December 18th, 2009 at 1:32 pm

    I didn’t know that. thank you

  32. Jordan writes:
    No. 32 — December 23rd, 2009 at 1:36 am

    When I run the one-liner in Mac Google Chrome, I get “Unknown”.

    Any chance someone could update the one-liner to work with Mac Google Chrome?

  33. superhei writes:
    No. 33 — February 9th, 2010 at 2:10 pm

    /a/[-1]==’a’ isn’t work on firefox3.6

  34. Gareth Heyes writes:
    No. 34 — February 9th, 2010 at 2:13 pm

    @superhei

    Yep Mozilla decided this was a security issue when I reported it so these techniques can no longer be expected to work in later versions of Firefox

  35. noob writes:
    No. 35 — February 18th, 2010 at 5:53 pm

    i was wondering why are you using ((/a/.toString+”)) instead of (/a/.toString+”) ?

  36. Gareth Heyes writes:
    No. 36 — February 18th, 2010 at 10:09 pm

    @noob

    Yeah probably a typo nobody is perfect 🙂

  37. hztny writes:
    No. 37 — March 19th, 2010 at 6:06 pm

    Yeah probably a typo nobody is perfect

  38. Damian writes:
    No. 38 — April 19th, 2010 at 6:16 pm

    FireFox keeps being detected as Chrome

    function getBrowser()
    {
    if( _browser == undefined )
    {
    _browser = (function x(){})[-5]==’x’
    ?’FF3′:/a/[-1]&&Object.getPrototypeOf
    ?’FF2′:/a/[-1]==’a’
    ?’FF’:’\v’==’v’
    ?’IE’:/a/.__proto__==’//’
    ?’SAF’:(/a/.toString+”)
    ?’CHR’:/^function \(/.test([].sort)
    ?’OP’:’Unknown’;

    /* not sure what’s wrong w/ the above oneliner.. */
    if( /a/[-1]&&Object.getPrototypeOf ) _browser = ‘FF3’;
    if( _browser == ‘IE’ && isIE8() ) _browser = ‘IE8’;
    if( _browser == ‘IE’ && isIE7() ) _browser = ‘IE7’;
    if( _browser == ‘IE’ && isIE6() ) _browser = ‘IE6’;
    }
    return USE_LOWERCASE_BROWSER ? _browser.toLowerCase() : _browser;
    }

  39. abhishek writes:
    No. 39 — April 29th, 2010 at 12:53 pm

    Hi,
    Nice trick for detecting browsers. I am adding this to my blog.

  40. 2web writes:
    No. 40 — August 15th, 2010 at 8:41 pm

    Nice artcile)
    Translated & posted.

  41. HP Bryce writes:
    No. 41 — September 8th, 2010 at 8:55 am

    This is sweet! I use ie and Fire Fox depending on what I’m doing or where I’m browsing. This will be great to keep peoples noses out of my browser!

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