Skip to content

Instantly share code, notes, and snippets.

@ste-lam
Forked from 140bytes/LICENSE.txt
Last active June 4, 2023 09:03
  • Star 16 You must be signed in to star a gist
  • Fork 1 You must be signed in to fork a gist
Star You must be signed in to star a gist
Save ste-lam/999166 to your computer and use it in GitHub Desktop.
base64 encoder w/padding

140byt.es - Base64 encoder

A base64encoder with padding, what shall i say more? This version now includes the amazing improvements made by Jonas Magazinius and LeverOne, for more details visit the "sla.ckers"-forum @ http://sla.ckers.org/forum/read.php?24,36342

If you are looking for a decoder give https://gist.github.com/atk/1020396 a try.

Example

	var 
		sigma ="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
	,	sample = "140bytes rocks!"
	,	encoded = (function(...){...})(sample, sigma);
function(
a, /* input text */
b, /* mapping table */
c, /* working block */
d, /* input char index */
e /* output text */ ){
for(
// initialize char indices
d=e='';
// cast d to int (floor)
// if the next input index does not exist:
// change the mapping table to "="
// check if d has no fractional digits
a[d|0]||(b='=',d%1);
e+=b[ 63 & c >> 8 - d % 1 * 8 ] // "8 - d % 1 * 8" generates the sequence 2, 4, 6, 8 (first value for d is 0.75)
)c = c << 8 | a.charCodeAt( d-=-.75 ); // note: "d -= -3/4" works too
return e
}
function(a,b,c,d,e){for(d=e='';a[d|0]||(b='=',d%1);e+=b[63&c>>8-d%1*8])c=c<<8|a.charCodeAt(d-=-.75);return e}
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
Version 2, December 2004
Copyright (C) 2011 YOUR_NAME_HERE <YOUR_URL_HERE>
Everyone is permitted to copy and distribute verbatim or modified
copies of this license document, and changing it is allowed as long
as the name is changed.
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
0. You just DO WHAT THE FUCK YOU WANT TO.
{
"name": "Base64Encoder",
"description": "A JavaScript Base64 encoder in 109 Bytes.",
"keywords": ["base64", "encode", "rfc2045", "sla.ckers", "btoa"],
"license" : "DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE",
"url" : "http://sla.ckers.org/forum/read.php?24,36342"
}
<html>
<body>
<script type="text/javascript">
(function(){
var f = function(a,b,c,d,e){for(d=e='';a[d|0]||(b='=',d%1);e+=b[63&c>>8-d%1*8])c=c<<8|a.charCodeAt(d-=-.75);return e}
, test = {
'' : ''
,'AA==' : '\0'
,'AAA=' : '\0\0'
,'AAAA' : '\0\0\0'
,'AAEC' : '\0\1\2'
,"Zg==" : "f"
,"Zm8=" : "fo"
,"Zm9v" : "foo"
,"Zm9vYg==" : "foob"
,"Zm9vYmE=" : "fooba"
,"Zm9vYmFy" : "foobar"
}
, error = 0;
;
for( i in test ) {
var r = f(test[i], "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/", "=");
if( r != i ) {
error++;
document.writeln( 'Expected &quot;'+i+'&quot; for &quot;'+test[i]+'&quot; but got &quot;'+ r + "&quot;<br>" );
}
}
if( error > 0) {
document.writeln( "<br>"+error+ " tests failed!<br>" );
} else {
document.writeln( "<br>Everything is fine!<br>" );
}
})();
</script>
</body>
</html>
@Kambfhase
Copy link

ris not declared and spills the global scope. Since you do have enough chars left that should be no problem though.

@jed
Copy link

jed commented May 31, 2011

this is still blowing my mind.

@atk
Copy link

atk commented Jun 11, 2011

This will not work in IE7 and older versions. Since only few people are using this old browser replacements, I would not consider this critical.

@jed
Copy link

jed commented Jul 11, 2011

hey @nignag, would you mind taking the comments out of your package.json?

@Jarod-
Copy link

Jarod- commented Jul 27, 2011

Any idea what I should change to make it work for IE7 and older ? In my company everyone is using IE<=9 BUT with IE7 compatibility mode (blocked by I/T), and this code doesn't work in that case :-/
Thanks.

@Kambfhase
Copy link

try chaning the bracket notation on line 16 and 18 to .charAt(). otherwise sneak up to your co-workers stations and install chromeframe. :)

@Jarod-
Copy link

Jarod- commented Jul 27, 2011

@Kambfhase yes it works like that. Thanks!

@jed
Copy link

jed commented Jul 27, 2011

wait, did .charAt work or did sneaking up on your coworkers work? nyuk.

@atk
Copy link

atk commented Jul 27, 2011

you could also use .split('') on both input string and translation map.

@LeverOne
Copy link

LeverOne commented Feb 3, 2012

109 now if you had not seen: http://sla.ckers.org/forum/read.php?24,36342,page=2#msg-42491
Here are the tests if anyone is interested: http://jsperf.com/base64-encode-js

@atk
Copy link

atk commented Feb 6, 2012

@LeverOne: (d-=-.75) looks like it can be reduced to (d+=.75)

@LeverOne
Copy link

LeverOne commented Feb 6, 2012

@atk
Unfortunately, not. This is a trick to prevent the concatenation, since d is a string initially. Therefore, d+=.75 == '.75', then '.75.75', etc.

@atk
Copy link

atk commented Feb 6, 2012

@LeverOne: thanks for clarification.

@tsaniel
Copy link

tsaniel commented Feb 18, 2012

@LeverOne: I always wonder how you find so many magic sequences. Could you tell us how?

@LeverOne
Copy link

@tsaniel
This process is almost creative, there are no special spells.

@atkach
Copy link

atkach commented Dec 23, 2013

Could you please explain me what this "d%1" in "a[d|0]||(b='=',d%1);". Why don't just "a[d|0]||b='=';"?

@ste-lam
Copy link
Author

ste-lam commented Apr 27, 2014

d%1 tests for fractional digits, so the check is necessary

@burkulesomesh43
Copy link

burkulesomesh43 commented Aug 10, 2018

Hi all,
I am using using esp idf environment on esp32 board. I want to decode url.
URL>>file:///F:/s?ssid=cabin+336&Passkey=Cabin336%40efc

In above url, 'Cabin336%40efc' includes '%40' which has its decoded value '@'
so how to decode this?
I tried to use base64.h library file from esp idf but gives an error..
fatal error: base64.h: No such file or directory

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment